If you're still taking Warriors questions:
He is my favorite character
Dudes trauma from being kidnapped as a kit leading him to become mistrustful of outsiders.
He was the first warrior Firestar named
Two of his sisters are injured early and become disabled (maybe meaning Frostfur gave them extra attention and Brakenfur was already a warrior so Thorn was kinda left by himself)
He builds this xenophobic group of friends (Dustpelt, Ashfur, Spiderleg)
(and definitely not gay for Ashfur at all but doesn't realize until well after he is dead. Then the drama of TBC and the Imposter) I really think he should have been a Light in The Mist instead of Greystripe
I don’t like Thornclaw very much I’m sorry… I think he’s boring at best and an insufferable ThunderClan nationalist at worst. I can see the plot you’re putting together for him but I can’t say he’s just someone he’s someone I’ve thought about a lot. All his siblings are more interesting than him and I strongly dislike his relationship with Blossomfall. I do think your points here make him more interesting and show how he becomes the cat he is but I can’t say it makes me like him per se lol