Because even the weakest avenger deserves some love now and again.

They're both (main) Hollow Ataraxia characters.

They are lovers canonically

( ͡° ͜ʖ ͡°)

Apparently the two (Caren and Angra) are in love, odd pair, I know, but I'm not against it.

I see, thanks for your explanation.

Too bad there is no exchange between them.

It's time to look Ataraxia now.

Yeah, I'm also disappointed that we didn't get to see them interact with each other even though Angra was the featured Servant here, but hey, at least we got some pretty good Hollow Ataraxia references here and there ( ͡° ͜ʖ ͡°)