Splinter/Shredder backstory discrepancies

[neatoman]

So I just got the season 1 set and I just finished disk 1 and there seem to be some discrepancies with the past of these two characters.

In season 1 it seems that Shredder and Splinter were war buddies (in a realistic modern war), their friendship fell apart partially due some unknown insults, Shredder challenged Splinter and the fight lead to a fire that killed Tang Shen. In that order.

In season 2, there was some kind of fantasy ninja war, Shredder was adopted from the defeated rival clan and was raised as Splinter's brother, Shredder became a villain due to finding out who his parents were, Shredder tried to assasinate Splinter but killed Tang shen instead and then the fight that lead to the fire happened.

These backstories are not necessarily in outright contradiction but they don't align perfectly. I have suspected for quite a while that Splinter (we really only know his side of the story, it's a little unclear what Shredder's side of the story is other than that Splinter is to blame) is a somewhat unreliable narrator, that he's either hiding something or his point of view might be a bit warped somehow.

What do think? Is Splinter's narative reliable?