While I absolutely love the idea, I don't think Harry would be as putty in Lucius' arms as you think. He was a smart kid and I doubt he would entirely trust Lucius. I think he would have been cautious and took whatever Malfoy Snr said with a pinch of salt. He'd probably be civil with Draco until it came to the sorting. While he might have agreed with being placed in Slytherin, I think he'd still be the Golden Boy who fought against Voldemort. He would, though, break the stereotype that all Slytherin wizards are evil. Heck, if he was placed in Slytherin after meeting Lucius, I think he would have started seeing the benefits of befriending powerful people and would have started rooting for inter-house communication much earlier.

Lena/Gryffindor/3