It started with a headache.
He didn't have a fever or any other symptoms, so he didn't do anything about it. Just painkillers and continue on with his work and meetings.
Then the headache lasted for a week.
It almost felt like something was trying to push through his head, almost like hair but much, much thicker.
But he had meetings and responsibilities. He was the ambassador for the Blade of Marmora and had a class of young pilots to teach at the Garrison. He was also the husband of the Captain of the Atlas, so Shiro's happiness was also at the top of his concerns. He had a lot of paperwork, and grades to put in and students to meet with, so what if his hair had been in the same braid for a week without being washed.
He showered every night, but now that his hair covered half of his back it took forever to wash.
He just didn't have the time until the end of the week and he noticed them.
As he was rubbing the shampoo into his hair his fingers grazed something...solid.
And the same thing on the other side of his head.
His hands shook as he finished washing the shampoo out of his hair and dried himself off just enough so that he didn't drip onto the floor of him and Shiro's bedroom.
"Shiro." Keith said, as calmly as he possibly could when he had no idea what the hell was growing on his head.
Shiro stirred under the covers of their bed and rolled over to face Keith, smiling as he saw his husband with a clean, white towel covering him and long ebony hair hanging loose.
"Hey, baby." He gave a weak smile, snowy white hair all ruffled and eyes heavy.
Keith didn't say anything. Couldn't. He was frozen in place, too afraid to tell Shiro what was happening and too uncertain as to what they would find when they looked.
Shiro's expression changed when all the color drained from his face.
"Hey, lay down, it's okay…" Shiro sprung out of bed and was immediately at Keith's side, supporting him under fear his husband would faint, and helped him to lay down on the bed.
Keith quickly got it out that he had felt something in his hair in the shower. He would never say he was scared- Shiro already knew he was by the look in his eyes and how fast he blurted everything out- but saying as such was a completely different thing.
Shiro took a deep breath and searched through Keith's mass of hair until he found it.
Shiro paused when he did, subsequently finding the other one about five inches from the first. Keith twitched when he felt the cold touch to the... appendages on his head. Keith could feel when they were touched, feel temperatures from them. They were part of him, there was no doubt.
"You ever seen a baby goat?" Shiro said suddenly, almost making Keith jump.
Keith's mind stumbled over words.
"W-what?" He finally managed to spit out.
Shiro fake coughed to buy him more time to think about how to respond.
"You know...the uh...the horns that baby goats have? Like the tiny ones that are just growing." Shiro's fingernails touched along Keith scalp, making Keith shake slightly as he realized what Shiro was talking about.
"I have baby goat horns." He said in a dead tone.
Shiro swallowed and nodded.
The Galran doctor touched down in the hangar that morning and met Keith in his and Shiro's apartment.
"You need to rest." The doctor said after examining the horns growing on Keith's head for nearly an hour.
"Is everything okay?" Shiro chirped in, concern lacing every word.
"It will be. It's common for Galra who develop horns to be delayed until they reach thirty in human years. Some get them when their fangs grow in and others don't get them for many years. The only problem is that since Keith is a hybrid, there's a bit of swelling and inflammation where the horns push through the skin. He also needs supplements to help the horns grow faster. It's almost like a baby teething- there's going to be pain until it stops." The doctor explained in a clean, professional manner.
"What about the... sensitivity?" Keith's throat dried up as he asked.
"It will get better as they grow. They will always be sensitive to hot and cold and gentle touches, but it will be much more muted than what they feel like now." The doctor used some sort of metal tool to hold Keith's hair back as he studied the degree of inflammation on his scalp around the horns.
"They will grow strong. The length and width is very promising for ideal horns. I don't predict any troubles with the growth, but if there is, give me a call. I'll come over as fast as I can." The doctor promised as he handed two bottles of medication to Keith and gave him instructions for taking them, before bidding them goodbye.
And Keith was left to deal with the fact that him growing horns was normal and he had to live with them for the rest of his life.
It was easy to hide the little buds at first- tie his hair into a bun, wear a hat.
But that was when his hair could hide the horns.
Once Keith took the medication the doctor gave him, while the pain decreased, the rate at which his horns grew increased.
Once he couldn't conceal it with hats or with his hair, he stopped trying to hide them all together. He explained it briefly to his class that it was a Galran biology thing, and neither the students or anybody at professional meetings mentioned anything.
Luckily, after nearly three months of pain and embarrassment of having to watch people stare at the horns like he had three eyes, the growth was done.
The horns were curved slightly before they dipped down and ended on a little loop. They were about the same color as his hair, and while he could feel everything that happened to them, his life no longer revolved around them. He could do what he wanted without fear and pain, because they were done growing and as long as he didn't look in the mirror he could forget it ever happened.
Until he takes a shower and is forced to see his horns like he's some kind of fictional monster that children see in history books and have nightmares about.
Shiro, however, called him adorable and kissed him until the pain fainted and he realized that if Shiro liked the horns, so did he.
Shiro loved him.
His husband loved him.
That's all Keith needed.