Well. It was very difficult indeed to pass up a target of any sort, particularly when boredom was beginning to set in. Not that Clint really knew why he was bored -- there was literally a house with portals to a billion different worlds and dimensions just a few blocks away. Something in him said he ought to not go in there too much without company though, because the stakes were high, and you never knew what could happen. That house and those doorways held too much chance, and Clint had never been very good friends with luck.
So yeah. A target. And sure, there was a dude already taking shots with a bow at the thing (and he was good, too!), but---
Well. He didn't see any reason not to join in. From a branch, some several trees away.