Loki learns quickly.
He learns that what Thor does is right and what he does is suspect. He learns that accompanying Thor on his adventures, however tedious they might be, gets him out of Asgard and away from Odin’s hard stare, and that when they return Thor’s bright presence and glorious tales of bravery and valiant battle allow him to go unnoticed.
He learns that if he uses his magic for warfare it does not arouse Odin’s suspicions, and that if he uses it to play tricks he can make Thor laugh and keep him from worrying. He learns that as long as he supports his brother he is safe, that as long as he does not act too much like himself he does not have to worry about Odin’s mercurial temper or the extra training sessions he might demand.
He learns that most of the court does not like him, does not trust him. This cannot be a recent development; the distrust is deep-seated and comfortable for those who practice it. They have disliked his un-Aesir actions for some time but have been unable to express it until Loki’s sudden fall from grace. Now that he is no longer protected by Odin’s approval the court is free to let him know how unwelcome and unnatural his interests have always been.
Loki learns that his idyllic childhood must have been an illusion. How could it have been so happy, so carefree, and turned so easily to this miasma of acrimony and bitterness if it had not always been a lie? He learns that it is less painful to go back and edit his childhood memories to include this new reality than it is to sit and wonder what went wrong, what he did wrong, what is wrong with him.
Clearly he has always been the less-favored child. Clearly he has always been tolerated rather than loved, ignored rather than indulged, included as an afterthought to his brother’s rightful glory.
What use is a second son, anyway? What possible use is a creature so ill-fitted to life in shining Asgard?