Not gonna lie, got a little misty-eyed during the scene at the very end.

Satsuki is always alone, even though she has so many people serving her, only one of them is even her friend at all (Nonon), and she doesn't spend down time with Satsuki either. Even Ryuko spends all her free time with Mako when she's not fighting.

We also saw that Satsuki can't quite handle her Kamui. Now that Ryuko and Senketsu are best pals, Ryuko barely loses any blood. Satsuki on the other hand, appears to get anemic just from daily wear. She has to take it off, secure it down and rest for a few hours.