Smashing the purple ooze after the brother's debated on whether to use it to turn themselves human again or not was seemingly a mistake in Raph's mind. Sure, he was the one who made the decision to ruin such an opportunity, but he was starting to regret it. Looking into his cracked mirror, he saw the same freak he did as a kid, just bigger and stronger, physically. Mentally, he still felt small, unwanted by everyone, even his brothers and especially Splinter. Leo was his favourite, not Raph. Everyone loved Leo, he was the hero, the leader, the favourite; Raph was his shadow, someone people only saw if they wanted too. No one cared about Raph, right? He was the useless one.
He was suddenly snapped out of such thinking when feeling a hand on his arm, it was you.