It speaks to the levels of fucked up that Jean is that when Eren looks at him, blood running down his face, open mouthed, it makes his dick twitch. There's no hiding the reaction since Eren's at level with it, but Jean plows on like that didn't happen.

Thank god the leather of their boots is easy to clean, although Jean slightly regrets not getting out of his pants first now. Whatever, he'll deal with it later.

Instead, with Eren's mouth open like a wound, Jean shifts closer with his other foot and presses his cock back inside, over his tongue. He doesn't push all the way in before he pulls out, just a little. Just to see the mixture of spit and blood on his dick before he sighs in contentment and rocks forward again. He presses until he's almost fully sheathed in Eren's mouth, just teasing the back of his throat.