Okay, so Raphael has been drinking the devil haterade for a couple thousand years (also, he might or might not have only gotten here recently), and be pretty on guard and disturbed about any sweet offers to ease all his self-inflicted pain. Probably because it's only audio. He holds onto his problems like a miser holds onto cash.

Thus he'll be rebuking the devil and here to watch and attempt to treat any and all transformations on a symptomatic basis, because otherwise he's just fiddling as Rome burns. In pain? Raphael can help. Bleeding profusely? Raphael can help. Really enjoying your new form/your newfound ability to work through your issues? ... Raphael will lineface and judge and maybe silently stew (or fight, if push really comes to shove), and be moved to try and figure out exactly what's going wrong and how to stop it.