All I want is machine sentience

Klein:

Suffers from erectile dysfunction. I’ve seen this headcanon float around and I really like it because Klein is a man who so obviously likes being in control but this is the one thing he doesn’t have control over. He’s very self-conscious about it and he’ll kick anyone out of bed immediately if they joke about it. He treats it with penis pumps and his own version of Viagra (basically mad science-ing a way to cure his ED). Open to using toys (like cock rings) that could help in the bedroom, but any partner would have to know how to be tactful about the subject in order for him to be onboard.

Klein is a busy man, so he prefers to have dates/sex scheduled. Not the most sexy thing in the world, but it gives him something to look forward to after a long work day and helps him prepare mentally and physically (going along with the ED headcanon).

Does not like surprises. Enjoys sex that's routine and predicable. A little spontaneity is okay if he really trusts and knows his partner well.

True intimacy for Klein has to be with someone he trusts. It’s difficult for him to open up to someone and it takes time for him to warm up to a potential partner, but once he does, he can be surprisingly needy, wanting to see that person and interact with them whenever he gets the chance.

I'm of the personal opinion that most people tend to be fluid when it comes to the Dominance/Submission/Top/Bottom labels, depending on mood, life experiences, partner dynamics, etc., so that's true with Klein as well. He leans dominant/sadistic with partners he views as disposable or beneath him. If he's in a bad mood, he might enjoy insulting/berating them, humiliating them, blowing cigarette smoke in their face or if he's being very mean, slapping them, hitting them with a ruler/pointer, or putting out a cigarette on their body (thanks @wires-skinned for that suggestion!) Picture "Evil Boss from Hell" or "Strict Professor" and that's how he is at his worst.

On the flipside, with partners he respects and trusts, Klein is more open to being vulnerable and being more sexually generous. After a long day of yelling and being disciplinary to people, the idea of just coming home and shutting off his brain and doing whatever his partner wants is very appealing.

Klein loves scalp massages and having a hand run through his hair. Gotta massage that big ol' brain of his to get to his heart.

Drinking can be a double-edge sword with Klein. If he's in a good mood, drinking will mellow him out and he’s more openly affectionate when he’s tipsy/drunk. But if he's in a bad mood, it'll bring out his more sadistic, domineering side.

If a partner upsets him, Klein will withhold sex and affection until the issue has been resolved (begging and groveling helps).

Cat-like in his affections. Klein is loath to admit that he enjoys human touch and attention as much as he does, but if he likes someone, he’ll signal it in more subtle ways. A hand that lingers too long on that person's shoulder, bumping into that person more often, leaning in a little too close. Privately he might go as far as climbing into that person's lap if they ignored him for too long.

Secret Sex Super Power: Oral sex. Klein is indeed the throat goat.😏

Speaking of oral fixations, Klein definitely has a smoking fetish. Considering this is the pseudo 50s and everybody was probably smoking, it's been his thing for a long time. Sharing cigarettes, having a partner blow smoke into his mouth while kissing, and just being in a cigar lounge with well-dressed, attractive people are all turn-ons for him.

Not necessarily a fetish per se, but Klein loves a classy dresser. The thought of peeling away the layers of clothing and finery to get to the person underneath is considered foreplay to him and turns him on immensely.

Klein's love language is gift-giving, so seeing his partner wear something he gifted them (whether that's jewelry or clothing or more intimate wear) that marks them as his, is also a turn on.

Not into pet names, but will tolerate it if he's been drinking and in a good mood.

Very clean and tidy and that extends to sex. The first thing he does after a sexual encounter is take a shower, brush his teeth, and use mouthwash, even if it's in the middle of the night. He won't demand that his partner shower with him (unless he's in boss mode), but he'd probably appreciate it.

Turn ons: Smoking, stylish clothing, cleanliness, being well-groomed, intelligence, maturity.