Roger hadn't been sure when he was going to be done with Eli, so he hadn't given Mariette a specific time when he would arrive. He had to go over to his best mate's place to help him with an experiment. And then that was followed by drinks. Roger didn't mind to helping out a friend, but what he'd really wanted to get out of his day off was some drinks, and hopefully a hook up.
And he definitely was hopeful, since Marietta had invited him over that night. So he'd only had a few drinks to loosen himself up, certainly not drunk, but he still used the floo at the bar to the closets floo station to Marietta's flat. At least the rest of the walk would completely sober him up.
Roger got to the door, and lifted his hand to knock. He'd also made a quick stop before getting to Marietta's to get her a small bouquet of flowers. He could still be gentlemanly even if he was here for a booty call.