hi i have 3 of them this probably will be a long answer-

haemal (my doc oc/daughter) shows affection mostly through gifting! shes not too good with her words so shell give you little trinkets and such she made in her spare time. shes also checks up on them (especially towards infected operators) and asks about their day and just strikes up a convo with them. also if they were working when she saw them then she would help them with the thing they were working on.
romantically she would be very clingy, like a magnet to metal kind of clingy. she would cuddle (insert name here) whenever she could and again shes not good with words so shed shower (name) with kisses instead but still sometimes compliments him (it isnt the most well constructed compliment youd hear but its the thought that counts). lastly, shell definitely invite him over for dinner, they are 'friends' after all :)

dawning will tell you that she likes you (platonically or romantically), you'll definitely hear from her if she doesnt hate you. she treats everyone the same as if they are all friends with her except for a few exceptions, depending on the operator. she also takes you out to drink or just hang out together. i havent thought of how she would show affection romantically but i can see her being super flirtatious towards her love interest.

for fritz honestly i would think hed still be his energetic self and will talk your ears off. hes somewhat loose with his words so he wouldnt even notice if he said something nice (if that mad any sense djsgdshgds-) nothing much to say about him since hes already way too friendly to everyone he meets whether they like it or not, so just imagine this 5'7 child is spewing out affection like a fountain.

fuck i wanna talk about all my ak bastards so this is going to be long
lazuli expressions affection very autisticly, usually via parallel play, but for more romantic affection they're very tactile, if they could have their hands on their partner, they are CERTAINLY touching them some how, usually prodding and just [grab]
zoloft- gift giving, both platonically or romantically
salem- also a more tactile person, everyone he likes gets hugs
backcountry- he is doge and he expresses affection like a doge, lots of tail wagging, very verbally and lots of hugs "hi!!!!! hi!!!! i love you!!!" energy
codeBLUE- romantically she'll offer to take them out for a drink, also uses a lot of petnames casually, for platonic she is just a lot... softer with them, more gentle
cyanide- really a "acts of service" kind of guy, he won't say "i love you" too often, but he will do your laundry without you even asking first. platonically he offers first
salem- everyone he loves, no matter how, is going to get a hug
i dont know if viridis can genuinely like anyone