Oh Bron, I have many mixed feelings for you.
1. Based upon my readings from the various Bron-related topics on the forum, I get the impression that Bron is one of the more polarizing characters in the fandom. Or, at least he was back when he made his debut in the series. What is your general impression of the explanation for why Bron was absent for so long? Do you feel that the explanation holds up under scrutiny?
Hmm... I honestly don't know. I remember a lot of people saying 'why didn't Bron go to the Great Valley when all of the leaf-eating herds were travelling there' and someone did mention the possibility that Bron
did go to the Great Valley, he just arrived before everyone else did. So... I think it's fine at first glance and it makes sense to Littlefoot but when you think about it, there's a few things that don't make sense. It could have been written a lot better.
2. What are your general impressions of Bron as a character?
He's pretty cool in LBTX, and I believe he does genuinely care about Littlefoot and is a good dad when he's around. He takes in all of those hatchlings he found with Shorty and he cares for his herd so I'd say his heart is certainly in the right place. Risking being cooked alive to save Wild Arms is not something I can say I'd do.

I'd say he tends to jump into danger without thinking because he wants to save others, although I wonder if that's something he picked up because he failed to protect his mate. All in all, I think he's a decent character, and in LBTX he's voiced by Kiefer Sutherland which is pretty awesome. He didn't get much screen time in XIV and thus he didn't get much of a chance to show any new side to his character, so... meh.
When it comes to him living with Littlefoot in the Great Valley, well... his herd is pretty huge and full of longnecks, and with that I don't think he can bring said herd to permanently settle in the Great Valley or else it'll be stripped of green food pretty quickly (I don't think many longnecks live there permanently). But, why he can't just train someone up to take over so he could leave them and stay with Littlefoot I don't know. Mouse's theory that he just has to keep moving however, I think is a good one. I wonder how many longnecks actually could settle down in one place permanently, and how many are migrators for life.
I wonder about his relationship with Littlefoot's grandparents too, which I think I brought up in another thread. They seem civil enough, and the grandparents seem happy that Littlefoot has the chance to have a relationship with his dad, but one does have to wonder if there's a bit of tension/awkwardness between them now that the bridge between them that was Mama Longneck is gone. I think they all feel guilt because all of them failed to protect her, but is there some bitterness? If there is tension between them, it might also be another thing that would make Bron feel too uncomfortable to go and live in the Great Valley. Given their interactions in the films, Grandpa seems to get along with him better than Grandma does, but I'd like to see more of the three together in the future to see where they really stand (although that conversation might be something better left to fanfiction).

Also, have a quick drawing of him and Mama (because everything I draw these days has to involve her lol) gazing into each other's eyes.
