Obi Wan Kenobi: Obi Wan somehow came up with the completely unique nickname "honey", because you're so sweet apparently. So you call him "bear", because bears like honey.
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Luke Skywalker: Luke decided to start calling you "newbie", since you were new to the fleet when you met, so it just stuck around. His nickname is "skyguy", self explanatory... he's a pilot and well, the last name.
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Anakin Skywalker: Anakin calls you "tiger", because you are fierce and drive ambitiously to do something. However, your nickname to him didn't require a deep reason... because it was simply "Ani".
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Han Solo: Han loves to call you "sweetheart", which he uses sarcastically mostly, but he truly thinks you're a sweety. In return, you love to call Han "hotshot", well because... he shoots first.
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Kylo Ren: Kylo typically calls you "wildfire", since you are usually found running wild and free or venting about something that ticked you off. So... You love annoying Kylo with the nickname "Red", since red is the traditional anger color and it sort of sounds like his last name.
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Boba Fett: Boba has a fashionable nickname for you; "girlie". You love to call Boba "flyboy".
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Captain Rex: Rex thinks very highly of you, and considers himself your bodyguard, so he calls you "queen". But all queens need a king, so his nickname is "king".