User blog comment:Omega natsu2/...One Year Has Gone By/@comment-4933386-20150127055022/@comment-7418318-20150127150628

There are a whole lot of shippers who'd disagree with you. :P

But of course you are right. The purpose of Crime Sorciere is atonement and self-punishment. Erza has already overcome her guilt over leaving her friends on the Tower of Heaven island, so she has nothing to atone for. She might blame herself for failing against Kyouka for a while, but that's hardly the kind of guilt that CS deals with.

She might become an ally due to similar aims, but I can't imagine Jellal letting her join. He even said it himself on two occasions: Erza walks in the light while he and CS walk in the darkness.