By any definition Diego-san is a lap cat. He loves to hop up onto a person's lap (doesn't matter who) and often doesn't stop there, climbing to one's hair if one allows it.
He loves to be petted and have the area behind his ears, and his forehead, scratched. He has a long impressive tail that I often run my hand (in an OK sign) all the way up and down and he seems to love that sensation.
And although he loves all the attention (demonstrated by his deep deep purr), he cannot sit still on a lap. If you stop petting him, or scratching him he will rub his face into yours. He'll climb all over you unless you let him know he already has your undivided attention.
Unlike Thompson and Theo, he will not sit on a lap for more than a few minutes. It's like when he wants love and attention he REALLY wants love and attention. But for the most part he's his own guy and he's quite content going off somewhere to be his own guy.