Are Tygra and Bengali brothers?
Personally, I don’t think so. Though they did refer to each other as “brother” a few times in the series, I always thought of it as more of a term of endearment they used because they’re both tigers. Kind of how women might think of themselves as being part of a sisterhood, etc. Furthermore, I never observed any other evidence from the series that would have suggested definite familial ties (i.e. either tiger making reference to a common parent or other family member, etc). Though I was set straight on the fact that just because Tygra is an orange tiger and Bengali is a white bengal doesn’t mean they can’t be related. I just think there’s not enough there to draw the conclusion that they are related. Although, if you consider the UK Annuals canon, then they are brothers – the Annuals state this is so outright.