can আপনি tell me what these abbreviation type things mean অথবা stand for?

AU: Alternate Universe. If আপনি put the characters you're a অনুরাগী of in a different universe.
For example: make অ্যাঞ্জেল and Spike human and go to high school with Buffy, who is not the Slayer.
Or: Make the characters from Gossip Girl vampires.

OC: Original Characters. লেখা a new character to introduce in an existing universe.
For example: write a new student into the Harry Potter universe.

Mary Sue: Mostly Mary Sue's are OC's that are perfect. In my Harry Potter example, the new student, Mary Sue, would be good at every class and quidditch, everyone would like her (from all houses), every boy will fall in প্রণয় with her... and ofcourse she will defeat Voldemort while looking like an angel.
There are different kind of Sues, but আপনি can recognize them easily: পাঠ করা a story with a Mary Sue is f*cking boring.

well i had one of my RPG charictors called a mary sue once...then a slight fight started...-_-" i guess it means making a charictor seem perfect then trying to push it on everyone else...i thought i was reasonable to think the a charictor raised দ্বারা জন্তু জানোয়ার could calm জন্তু জানোয়ার down, but apparently not to them. this is word 4 word what they said.
A Mary Sue (sometimes just Sue), in fanfiction, is a fictional character with overly idealized and hackneyed mannerisms, lacking noteworthy flaws, and primarily functioning as a wish-fulfillment ফ্যান্টাসি for the লেখক অথবা reader. Perhaps the single underlying feature of all characters described as "Mary Sues" is that they are too ostentatious for the audience's taste, অথবা that the লেখক seems to favor the character too highly. The লেখক may seem to push how exceptional and wonderful the "Mary Sue" character is on his অথবা her audience, sometimes leading the audience to dislike অথবা even resent the character fairly quickly; such a character could be described as an "author's pet".

While the label "Mary Sue" itself originates from a parody of this type of character, most characters labeled "Mary Sues" দ্বারা readers are not intended দ্বারা authors as such. Male Mary Sues are often dubbed "Gary Stu", "Larry Stu", "Marty Stu", অথবা similar names.

While the term is generally limited to fan-created characters, and its most common usage today occurs within the অনুরাগী fiction community অথবা in reference to অনুরাগী fiction, original characters in role-playing games অথবা literary canon are also sometimes criticized as being "Mary Sues" অথবা "canon Sues," if they dominate the spotlight অথবা are too unrealistic অথবা unlikely in other ways.)

AU - alternate universe. basics if something is non-canon (I'm pretty sure), like OC sisters/brothers, not following timelines and such.
OC - other character
Mary Sues are basically characters who are too perfect and cliché - আপনি know, they have it all and so on and so on. like Bella রাজহাঁস for example.