mannerist (n.)

"excessive or monotonous use of distinctive methods in art or literature," 1803, from manner + -ism. Meaning "an instance of mannerism, habitual peculiarity in deportment, speech, or execution" is from 1819. Related: Mannerisms.

Perhaps few of those who write much escape from the temptation to trade on tricks of which they have learnt the effectiveness; & it is true that it is a delicate matter to discern where a peculiarity ceases to be an element in the individuality that readers associate pleasantly with the writer they like, & becomes a recurrent & looked-for & dreaded irritation. But at least it is well for every writer to realize that, for his as for other people's mannerisms, there is a point at which that transformation does take place. [Fowler]

word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.

Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.