There was very little for him to do that Frankie hadn't practically done for him. But human beings had been having sex for hundreds of years, in probably just about every place and position imaginable (not to mention a few that were well beyond the imagination, no doubt).
Only a slight adjustment found him buried inside her, still kissing at her neck as he began to move against her body. A condom would have been a good plan, but at this point it became blatantly obvious that they weren't planning any aspect of their little get together.
There were a lot of floors to go up, the only reason he ever got much exercise at all. Gus pushed himself into her harder, a few low grunts escaping with the effort.