The first thing Clyde notices when he shows up to visit Luke at university is the gigantic sprig of mistletoe hung right in the middle of the corridor a few doors down from Luke's. As big as it is, though, it looks awfully scraggly. The tendrils are long and look almost vine-like, and it doesn't have nearly as many leaves as it should; it's really quite an eyesore.
Luke, however, takes no notice of it. Clyde makes sure to give it wide berth, but Luke just walks right under it. There's another boy passing them, and much to Clyde's surprise, Luke and the other boy pause to brush lips quickly before going their separate ways. Clyde stops dead, trying to process the almost-casual display of affection he's just witnessed. Luke stops a minute later when he notices he's lost Clyde.
"What's wrong?" he asks, a puzzled frown on his face.
Clyde can feel his mouth hanging open, and he snaps it shut quickly, hurrying to catch Luke up. "Who," Clyde winces as his voice cracks, "who was that?"
"Oh, um, Danny, I think? He lives two floors up."
Clyde frowns, which Luke thankfully doesn't see, since he's busy unlocking his door. It isn't like Luke to be so free with his affection (not even with his best friends, really), so Clyde can't quite figure out how he's apparently fine with kissing a near-stranger, especially out where anyone could see them.
Clyde absently notices that Luke's room is nice (if a bit small) as he tosses his bag in a corner. After that, though, he doesn't know what to do. He desperately wants to be anywhere but alone with Luke right now, because he knows the conversation he has to start – really, that display in the corridor was just not normal for Luke, and abnormal usually means nothing but trouble – and he isn't at all prepared for that level of awkward.
He opens his mouth to start, even though he has no idea what will come out, but Luke cuts him off before he manages to say anything. "Want a tour of the rest of the university?"
Clyde knows he should decline, should instead try to find out what's going on, but Luke looks hopeful and excited, and Clyde really, really doesn't want to have that conversation anyway. "Sure, mate. That'd be cool."
The university actually is pretty cool, and Luke acts so much like normal that Clyde begins to think maybe he imagined all that stuff earlier. They spend a long time wandering around, while Luke gives an almost running commentary of everything he's been doing since he got there. And not that Clyde would ever admit it, but he's glad to hear mundane stories about classes and homework and all the things they used to do together; it makes it seem almost like he's been here for all of it.
By the time they make their way back to Luke's dormitory, Clyde is pretty tired. He's looking forward to lazing around, maybe watching a bit of telly. He's not even thinking of the mistletoe as they walk back, but the second they're in the corridor again, he can't think of anything but. Because this time, there are two boys standing underneath it, easy as you please, and they're really snogging. Nothing like that apparently half-hearted kiss Luke had earlier.
And Clyde supposes it's possible they're really just…boyfriends or something, but it's kind of suspicious timing. Not to mention that, well, who would put mistletoe up in a boys' dormitory, anyway? As loathe as Clyde is to admit it, he really needs to talk with Luke about it sooner rather than later.
Maybe in the morning. Yeah, morning will work.
The next morning, it still takes Clyde hours to work up the nerve (and come up with something to say) to bring it up.
"So, you know that bloke you snogged yesterday?" Possibly not the best opening gambit, but it's the best he can do on short notice.
"The…what?" Luke's got on the confused face Clyde has grown less and less used to seeing the longer they've known each other, which means that somehow, he really has no idea what Clyde is talking about.
"Right after I got here? Under that ugly mistletoe in the corridor?"
"We passed by him, but I don't remember any kissing."
"What, seriously?" Luke nods. "But you know the mistletoe I'm talking about?"
"Okay, and have you ever kissed anyone under it? Or seen anyone else kissing under it?"
Luke goes a bit glaze-eyed as he thinks about it, and it takes him a long time to shake his head. Clyde sighs; of course this wasn't going to be that easy.
"Okay, look. You obviously don't remember the kissing, but it happened."
"Maybe we should just call Rani and have her ask Mr. Smith. Has K-9 noticed anything strange?"
"K-9? I don't think I've seen him in awhile."
"What?!" Luke not knowing where K-9 is is so beyond wrong. Clyde's got his mobile out and is phoning Rani within seconds. Normally he'd have called Sarah Jane for something like this, but she's out working on a project of her own. Besides which, it's probably better that she doesn't know that K-9 is missing.
"Rani, I need you to go over to Sarah Jane's and get Mr. Smith online."
"What's wrong? Is Luke okay? Are you okay?"
"Yeah, we're fine for now, but something weird's going on."
"All right, I'm almost there. What do you need me to do?"
"I'm going to send you a photo of this scraggly-looking mistletoe, and I want you to show it to Mr. Smith, see what he comes up with."
Clyde nips out into the corridor and snaps a photo with his mobile, sending it to Rani. "Did you get it?"
"Yeah, just a minute. I'll have Mr. Smith take a look at it."
Clyde waits impatiently for Mr. Smith to complete a database search.
After a moment, he hears Mr. Smith's voice, loud and clear. "This species is known as the Tristerix. They are a plant-based lifeform originating on the planet Tristeris whose first known visit to Earth was two thousand years ago. Reported sightings of the Tristerix usually confuse them with various Earth-origin species of mistletoe."
"That's it! Has to be," Clyde says excitedly. "Does it have any…weird effects on humans?"
"The Tristerix have been known to affect the memories of those they feed on, as well as having the ability to attract prey into their feeding range."
"Feed on? These things eat people?!"
"They feed on affection generated by close physical contact."
Clyde lets out a small sigh of relief. "So, what you're saying is that it's feeding on everyone kissing each other?"
"That's what it sounds like," Rani chimes in.
"Do we need to kill it, then, or what?"
"Well, it's not really hurting anyone, is it?"
"Actually, over a long period of time, the Tristerix' feeding has been known to be fatal to the victims."
Clyde really hates when Mr. Smith says things like that. "All right, we're killing it. Now we just need to know how."
"Looks like there's any number of ways," Rani says, "but the easiest would probably be to burn it."
"We can do that. Thanks, Mr. Smith. Rani, I'll phone you later to let you know how it goes."
"Okay, talk to you soon."
Clyde hangs up, and when he looks around, Luke is nowhere to be seen. He hurries out into the corridor just as Luke shows up with a broom and a metal rubbish bin. He hadn't even realised Luke had been listening in on the conversation – he'd been kind of worried about dealing with the evil mistletoe – but here Luke is, complete with the perfect tools for taking it down and burning it.
"Wow, that was fast."
"Best to get this done quickly, yeah?"
Luke's smile is strained, which yeah, Clyde is sure he'd feel the same way, too, if an alien had been feeding on him for the past month.
"Yeah, let's do this."
It's the middle of the afternoon, but it's also a Saturday, so the dormitory is quiet enough that they can probably get through this without being interrupted. Luke shoves a pile of paper into the bin and produces a box of matches from somewhere in his desk. In the corridor, they situate the bin directly under the Tristerix, and Luke stands as far away as he can reasonably manage, ready with the matches.
Clyde tries to keep as far away as possible, too, but even with a broom, his reach only extends so far. He inches in closer, and the nearer he gets to it, the more he begins to feel its influence. It's like an invisible string is pulling him along, and it's leading him directly toward Luke.
Luke must feel it as well, because suddenly they're right next to each other. Clyde notices vaguely that there's a fire going in the rubbish bin just before he loses the will to resist the Tristerix' pull and kisses Luke square on the mouth. He's still frantically trying to knock the Tristerix off the ceiling, but even as he and Luke are kissing, things are beginning to seem a bit fuzzy.
He's not sure what he's doing, or why, but after a few seconds, he hears a loud thump. It takes a moment for his mind to clear, but once it does, he finds that he and Luke are stood next to a rubbish bin filled with smoldering plant remains, snogging as if their lives depended on it. They break apart hastily, and Clyde suddenly doesn't know what to do or where to look.
"I should probably," Luke starts shifting the bin toward the door at the end of the corridor, presumably taking it to wherever it had come from.
"Yeah, I'll phone Rani," Clyde mumbles.
He makes his way back to Luke's room while he talks to Rani. Luke comes back in just as he hangs up, and Clyde can't think what to say as the awkward moment stretches out.
"Thanks for saving me from the Tristerix. It might have…" Luke trails off, clearly not wanting to bring up the fact that it might very well have ended up killing him.
"Aw, well, it's nothing you wouldn't have done for- mmph!"
Luke's lips are suddenly attached to his again, and it's so much better this time around, knowing it isn't a 'have to', but a 'want to'. Luke pulls back after a moment, flushed and pressing his fingers to his lips, as if he can't believe that just happened, as if he hadn't been the one to initiate it. He smiles at Clyde a little shyly, and yeah, Clyde thinks this will work out just fine.
And really, he's almost actually grateful toward the killer mistletoe that brought this about.