It's not that he cares, He really doesn't. He didn't want to get involve with him.

But seeing him like this in a brutal injured state, He knew he had to help him.

He did help him in this Mission with his stock knowledge on Medical Jutsu,They we're the only ones who knows that night, That this interaction isn't the end, rather just the beginning of it.

"I need your help again Shikamaru."

"Unexpected Connection and Attract"