So maybe Sebastian doesn't just look on Ciel as his master or a soul to consume. Sometimes he finds him funny or interesting, even when he doesn't want to, and when Ciel actually is in danger, it's more than just professional pride that pushes Sebastian on.

Prompt is Sebastian is a little harsher than he needed to be in killing the people/demons/other beings that have kidnapped Ciel this time. Ciel is surprised and confused. Up to filler whether he eventually figures it out or not and how he reacts to it and whether it's pairing or gen.