User blog comment:Skyzy/The 100 Season 3 Trailer/@comment-26247132-20151215223038/@comment-26247132-20151215235835

She did say he was on the wrong side. People are saying that it's because he's undercover and she doesn't know it, which I think is out of character for Bellamy not telling her if he is undercover and she is that upset.

Instead, he just takes the beating like he deserves it, meaning he probably does deserve it. Here's the thing with Pike: Bellamy is anti-authoritarian as proven all throughout S1 and S2 and the Council killed his mom and locked away his sister before "floating" her to earth with the other delinquents so he has a lot of resentment there, still. This is all speculation, of course but then Pike shows up (I'm guessing from another Ark station) and starts unionizing the rest of the Sky People and Bellamy agrees with there needing to changes but then Pike goes too far (locking away "enemies" like Sinclair, Kane, and Lincoln) and Bellamy doesn't/can't stop him or stops him too late.

The other theory is that he is (also) on opposite sides of Clarke (with the Ice Nation against the Woods Clan is the general assumption), which makes him on the wrong side of Octavia (who identifies more with the Woods Clan at this point than with the Sky People who she never had any interaction with prior to coming to earth). And because she gave up her chance to belong with the Woods Clan for her brother at the end of S2, it has to really hurt that now he's fighting "her people."

Either way, Lincoln is in a precarious position and so is my heart. :-P