we don't talk enough about mei nianqing and what he was on when he strolled into xianle kingdom 800 years ago and proceeded to give himself a name that's honestly on the same level as hong hong'er/wuming naming himself hua cheng for xie lian.
buckle in for a quick lesson to comprehend the true extent of 2000+ years of yearning:
梅念卿 (mei nianqing) is the alias that guoshi made up in order to become the xianle guoshi. the character for the last name, 梅 (mei), means plum blossoms, and we will get back to it at the end.
念卿 (nianqing) is his chosen given name. the first character, 念 (nian), means "to miss [someone/something], "to yearn/pine, or long for."
for both of those definitions, 念 is most often used as 想念 and 思念
it's quite on the nose, but there aren't really any other interpretations for the first character. however, 卿 (qing) is where it gets super interesting. there are several common usages/meanings associated with the character 卿.
the first is used as a well-known form of address by an emperor towards a close lord or advisor—爱卿 . for those of you who have a bit of background in chinese, you might recognize 爱 as the character for love, but i do have to caution it doesn't have hold romantic suggestion in the typical historical usage (ie. non danmei historical setting). 爱卿 is really just a an affectionate way of referring to an emperor's subordinate that shows trust and closeness, like a very royally sophisticated "you're my bro" (in very, very layman term).
sometimes, in a variation, instead of 爱卿, the emperor will refer to the close subject as "_last name_ + 卿".
so for mei nianqing's example, if mei had really been his real last name, jun wu might have once referred to mei nianqing as 梅卿 (mei qing).
on the other hand, the second usage is as an affectionate form of address between husband and wife—卿卿. calling someone in an english equivalent would be something like "dear" or "honey". supposedly, there's a related usage of 卿 that can be used between very good friends, but i have to stress that it's really, typically overwhelmingly romantic in nature.
bonus: the chinese idiom 卿卿我我 is used to describe very intimately affectionate behavior (PDA) between couples.
basically, the character 卿 is used as a way of referring to someone, with different usages referring to different types of "you". think of it like this: one is saying "hey, you [my trusted subordinate]". the other is "hey, you [my dear]".
so together, 念卿 (nianqing) means "to miss [you]". the clever thing about this, though, is that depending on the usage, it could either refer to mei nianqing missing jun wu or the other way around.
the second usage of 卿 (qing) is used equivalently, in both directions, between lovers/"very good" friends. think about how you and your partner can both call each other "dear" or "honey". so the missing 'you' in 念卿 could refer to either person in the relationship.
but for the first usage (爱卿), it is only used by an emperor/prince towards someone lower, so the person being missed must be mei nianqing, since mei nianqing couldn't use 爱卿 to refer to jun wu, who was royal. interestingly, this usage is more likely the intended one, in my opinion, because realistically mei nianqing and jun wu never confirmed that they acknowledged any feelings between them beyond prince-old friend/subordinate and mei nianqing seems lowkey in denial that he's been in a 2000+ year situationship with a ghost king.
"you're not like him [jun wu] in that sense, little highness" my 🏳️🌈 ass, but i digress.
now why would mei nianqing name himself something that essentially means to miss himself? it sounds a bit egogistical to assume jun wu misses him? well, maybe, even after wandering for so long, it's not so much a statement, but a silly, foolish hope he still holds that jun wu misses his 爱卿, his old follower and friend.
or, coming back to his chosen last name, 梅 (mei) means plum blossoms, and maybe it does represent jun wu in mei nianqing's heart. but 梅 (méi) is also a homophone of the word 没 (méi), which means "no," or "doesn't." they are homophones down to the same tone.
in which case, if you say his full name out loud together, 梅念卿 (mei nianqing) acutally reads '[i] don't miss you', so maybe guoshi's name was actually picked out of a self-deprecating scorn towards himself, because he knew he was never enough for his highness of wuyong, that he wasn't missed by his prince in the 2000+ years apart. so he chose a name that would remind himself of that everyday.