regulus absolutely detested being around sick people, if you mentioned the beginning of a high temperature or sneezed continously around him he wouldn't touch you with a ten foot pole until you got better.
this rule however, had two exceptions: walburga and barty.
with his mother, it was like this: walburga didn't get sick often but she did get the occasional dizzy spells and you could count on finding regulus by her side everytime a headache flared. he'd just hover near her bed quietly, almost like a waiting servant ready to fulfill whatever request she had. since walburga was never truly sick, not in the traditional sense anyway, regulus didn't really think this exception applied.
with barty it was a lot different. his boyfriend didn't get sick much either but when he did it was like all the symptoms just amplified ten times. he'd have the entire package: sore throat, runny nose, splitting headaches. but for some reason, regulus still stayed by his side throughout all of it. he'd bring barty breakfast before class, visit him in the infirmary and even lay down next to him on occasion, letting the blond lean against his shoulder. regulus isn't sure why he felt compelled to stay, but he didn't question it. he just stayed.