I don't. Any Steele that takes Sub Sera, in my head, is a bit of an asshole. The meta reason to get Sub Sera (unless you just gotta catch 'em all) is that you're annoyed that Sera wants to make you her bitch and you want force feed her a little humble pie in the shape of Steele's dick. If you're catch 'em all, the how and the why will not bother you at all.
Del is another matter. He's boned no matter what Steele does. There's no option to help him that doesn't involve exploiting him in some way. Leave him at Tarkus where he makes shit pay that probably won't even handle the interest on his debt or get him enjoying having his ass tapped. Do the latter and he ends up with Kally and is much happier. Reaha is in a similar situation, but much more drastic. If you just pay to screw her, you might not understand how unhappy she is because when you interact with her, she's dang near trippin' on pleasure patches. Still, it doesn't take a genius to figure that maybe being tied down to let her tits get to ginormous sizee wouldn't be something Reaha likes.
Steele may be the PC window into TiTS, but they still have a (broad) personality. For example, Steele does have a little angst about being a tailor groomed heir (via Charumine and Shade sister talk). Steele is also quite likely pansexual, regardless of player choices.
EDIT: Also, it's indentured servitude, not slavery. Slavery is illegal! /s