"nZ" specifically as a title. While the lowercase refers to the younger letters being the focus and the fact that it's n refers to the episode starting with a young N saying his name, it also ties into the ABCs song that appears throughout the series, which ends with "W, X, Y and Z," and "n" is sometimes used as a short-hand for "and."
When L fired O at N, a brief flash displayed the word "NO," and most of N's friends had run away at this point. They were telling him that he has no friends.
In the final episode, a sad version of The ABC Song is played, the final line of said song contains the lyrics "Now I know my ABCs..." and seeing as we've just finished watching a series that portrays the alphabet as actual characters - we really do "know" them now...
This very lyric is also used as the title for the epilogue following "nZ", befitting for the true series end.
As someone on Youtube pointed out, the genius character building through which punctuation F cries: At first he cries the period because he thought that would be it, as the period represents the end of something. Then he cries the colon when he realizes there is more beatdown to come, as the colon implies more is on the way. As such, the next two particles he cries are the comma and then the asterisk, both of which represent multiple parts in a group. Then when N, F's best friend, does not help him, he cries the question mark, because he can't believe what has just happened and questions it. Then, most symbolically, he cries the semicolon, which colloquially means, "My story could have ended here, but it kept going," symbolizing F's new desire for revenge. And lastly, he leaves behind the exclamation point as he runs away to show that he's serious about this, it wasn't beat out of him, he naturally generated it on his own. And of course, to show how this was all planned from the start, the powers that each letter obtained were beat out of F by that very character - L got the period, O got the colon, M got the comma, X got the asterisk, and because N hurt F emotionally, he got the semicolon (P got the exclamation point because she was there.) By the color, F was supposed to keep the question mark, as that was generated by him alone, but instead he ran off and it was picked up by Q, who by obtaining the question mark, learned the answers to every question surrounding this story, and as such has been trying to warn everyone the whole time, but was too slow and thus couldn't catch up, leading to the the tragic events of the series. So tragic that Z, revealed to be the world that the others inhabit, is in tears, having cried an ellipsis that orbits around it, representing waiting and silence, as Z was powerless to stop any of the calamity that unfolded/would unfold.
The epilogue begins with Q and Z combining their ellipses and question mark gems to change the past. "...?" is often tacked on to "The End" to illustrate that the story will continue. What did Z end off his episode with? "Zeend."
Furthermore, "Zeend" sounds like a combination of the two official pronunciations of Z: "zee" and "zed."
Of course N and Z would work well together: N looks like Z when rotated 90 degrees and vice versa. In addition, N is orange and Z has blue shading: They're complementary colors.
As pointed out by a YouTube comment, Q and Z are the least used letters in the alphabet, but ironically the most important characters in the story.
Notice how the letters that beat up F in “Nz” are attacked/killed by F in the future.
C bites F, causing F to rip C apart.
J shoots out F’s teeth, causing J to get obliterated by F shooting I’s bullet at him.
I jumps on F, causing F to jump on I. (Also kidnapping him.)
X spins himself into F, causing F to chew X to death.
T slams into F, causing F to hit and trap him later on.
E uses D to hit F, causing F to hit E with D. (Also kidnapping both.)
Why is Q so slow? Because when singing the alphabet, you say "LMNOP" quickly, and then slow down once you reach Q.
X uses the asterisk gem to duplicate himself. Theoretically, he could spell "XXX," which is used to represent something sexual or obscene. And what is the asterisk also used for? Censoring vulgar things!
In "D", when F stands to the left of D, it looks like "f'd," which could be short for a swear word that accurately describes how bad D's situation is.
Z can use the ellipsis gem to turn back, or undo, time. And what does Ctrl-Z do on computers? Undo.
G and P's son is only capable of saying "goo goo". And that starts with G, the letter he is.
Also, if one takes a closer listen to Baby g's cooing, they might notice he's actually saying his name in morse code. Much like his father.
V being able to fly makes sense when you consider that in some artsyles, birds in backgrounds are sometimes drawn with V-shapes to save time, with this shape representing the bird's wings being up in mid-flight.
In the retconned timeline, everything seems all well and good, to a degree... but not only does N still remember and have to live with the traumatic events of the original timeline, but he is the only factor stopping it from happening again.He is F's entire stability. That has to be a lot of pressure on the poor letter.
Also, N also used to be friends with R, I, E, D, and S, and now it doesn't seem like he is anymore.
By Number Lore, F and N's once wholesome friendship had turned toxic. F still despises the other letters, ignores N's pleas to go help them and then tries to keep N from leaving him. Their ampersand gem splitting in half is symbolic of their broken bond. This is pretty much Truth in Television for how grudges can destroy even the healthiest relationships.
It's likely that the cracks on Z were formed by T constantly digging through him. Considering that Z is a living planet, does he feel any pain from this?
In the original timeline, G and P seemed to live separately, as the latter was part of the LMNOP squad. But in the new timeline, they raise a child and share a house together. Just like with F and N, it's possible that L, M and O pressured P into joining them instead of G (who was seen as inferior due to lacking powers), and N could do nothing but watch and relive his own friendship separation.
