It’s impossible to explain it without spoiler:
The little bear lost the mother due hunter… and kinai (the human-bear) felt sorry about the story…
Same for Tera: the Tera’s group killed the family of the young one in the fire. But after what he heard, he is now feeling sorry and guilty
I think the “best of luck” is for this: it will be not easy for him to forgive himself
spoiler for brother bear
kenai (large bear) was once a human but turned into a bear after some incident. i forgot. koda is the little bear. hes a real bear
koda is now an orphan because his mother died at the hands of kenai i think. kenai had an older brother who died becaus of little bear mother. kenai killed the mother bear to avange his brothers death
when he later found out he felt guilty
same as tera. he may have been involved in the boys parents death
https://imgur.com/a/EEsdIa0