The surprise is expected. The lack of resistance, slightly less so. Not entirely unexpected, not after how well Serph continues to react to more casual affection, but still. The John thing, and all. Jack is not going to be the same kind of kisser as someone who had seconds before been fighting anyone.

But, it's nice. He's kind of wanted to kiss Serph for a while. He didn't expect to be doing it for magic reasons, but he'll take it, even if it's the only one he gets.

It's only a beat later, then, that Jack deepens the kiss, leaning up and opening his mouth to Serph's lips. The buzzing energy blooms up between them, cool and crisp on the tongue, almost exactly like the phantom fire, and if Serph responds by opening his mouth to accept it, a burst of rejuvination will rush into him.