Jealous!Piccolo would include...
...Piccolo gets jealous pretty easily - he’s a giant green alien man, it’s only natural he’d have some insecurities about you - but he’s not much for showing it. He generally wears his feelings on his non-existent sleeve, but not his jealousy.
...him usually getting jealous when you’d rather spend time with someone else than visit him on the Lookout like normal, but at most, Mr Popo and Dende would send each other knowing glances when Piccolo would start meditating a lot more, the creases between his eyebrows just a little bit deeper.
...since Gohan tags along a lot, he would often try to use “Gohan’s been complaining that he hasn’t seen you” as an excuse, and with you not being completely clueless, it was obviously what he was doing.
...him just looking more uncomfortable around people if you just-so-happened to be joking around with some human man. It takes you a while to see that his usual grumpy-face was resting on the man more than anyone else, making you chuckle.
...you knowing Piccolo well enough to not just bring it up out of nowhere, and instead, just offeringPiccolo to leave the crowd with you. He’d happily agree - well, as happily as Piccolo can nod.
...his jealousy more-so happening subconsciously whenever he wouldn’t get to see you as often and it taking you time before you were able to catch the tell-tale signs. So, as soon as he’d be more grouchy, you’d just start making more time for him and he’d quickly seem more friendly to everyone.
- However, whenever he’s getting annoyed from unreasonable things, like you choosing to train with someone from the normal world, you’d bring it up to him when you’re alone.
...you always be strangely amused by how shocked he looks by the idea that he was actually jealous, but he’d reluctantly apologize and you would just sweetly assure him you love him and he has no reason to be jealous.
...him still never really being conscious about his own jealousy, even after knowing about his tendency for it, but usually being sweeter in bed and being more compassionate despite his snippy-ness, as if he’s subconsciously trying to win you back.
...it making you sometimes want to prolong telling him, but sighing in defeat when you remind yourself he hates feeling jealous.