Dean was up as soon as he heard the loud crack, bounding to his feet and moving to try to help steady Seamus - and check to make sure he was all in one piece. Dean wasn't the strongest of wizards, but he'd taken to apparation better than Seamus, somehow. Which he'd probably have been more likely to point out and tease him about if he wasn't actually a bit worried that Seamus MIGHT end up in pieces.
The tree caught Seamus before Dean could, and he just straightened, grinning when he looked Seamus over. "I think the hem of your left trouser leg's missing, but you look all right otherwise. Well. I mean you might have chopped off a bit of hair, but who could tell with that haircut?" he teased.
His neighbors were mostly out at work or the like, and his brothers and sisters were inside, so Seamus' loud entrance went unnoticed, luckily enough. People were good at looking away at things like that anyway, though. They saw someone pop up in the middle of their neighborhood out of no where, they just convinced themselves they'd missed them walking up, or climbing out of an car.
He clapped his hand on Seamus' shoulder, squeezing affectionately once. "Good to see you, mate. Missed having you about. How's things at your dad's?"