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So you've got some chairs, some tropes, and some complaining here.
"Destined" character fulfills their purpose or gets out of it, now has an open schedule: So What Do We Do Now?, Post-Script Season
Character Development for characters like Cable who started out as a walking plot device and became fully-fledged characters over time- sort of the narrative version of Grew Beyond Their Programming.
Aborted Arc if it really is dropped and never brought up again, but comics LOVE having a bunch of unfired Schrödinger's Gun options floating around to draw on for a good Crisis Crossover or major plot arc. The Clone Saga in the mid 1990's was the resolution to a plot arc that started in 1975 and left behind a number of loose threads, for instance.
Temporal Mutability for the eternal roulette game of whether you've actually prevented the Bad Future or averted your destiny, merely delayed it, or inadvertently set it all in motion. Prime fodder for the Schrodinger's Gun thing mentioned above. (IE, One of these days Cable is probably going to fight Apocalypse. The question is when and how, and what parts people are going to complain about.)
Edited by Scorpion451
Ok. Thanks for the help.
I'm thinking of a trope where a writer creates a character to fulfill a certain purpose, interacts with long-established characters, but their story arc is either aborted or cancelled (worst case scenario), or fulfilled (best case scenario). After accomplishing his purpose, the character remains in the universe, but does not seem to fulfill any relevant purpose.
This is not Reimagining the Artifact, but, to my mind, it can be used to salvage the character. A Retool may also serve to revitalize the character.
A few comic examples: 1) Black Swan - introduced by Jonathan Hickman during his dual Avengers/New Avengers (2012-2015) as the sole survivor of a universe that fell to a phenomenom called Incursion. The incursions happen in 2015 Secret Wars, and Black Swan appears later as part of Thanos's circle (Proxima Midnight, Corvus Glaive, etc.).
2) Hope Summers - as part of the long term "Mutant Messiah" storyline (2006-2010, 2012), mutantkind is depowered by the Scarlet Witch (House of M, 2005; Decimation/The 198, 2006). Hope is born as the first mutant after the mass depowering of mutants and is fought over by several mutant factions (Messiah Comple X, 2008). Cable takes her to the future, since she is destined to be some kind of "Mutant Messiah" who will rescue mutantkind from the brink of extinction (Messiah War, 2009). Cable and Hope return to the present time; Cable apparently dies, and Hope begins to bring in a new generation of mutants (Second Advent, 2010; Generation Hope, 2011-2012). She stars in 2012 Av X, but flounders until being given a new role in Hickman's Krakoan Age (2019-2021).
3) Cable - despite being introduced in the tail end of the 1980s, in New Mutants, his mythos, IRRC, would only be firmly established in 1992 crossover X-Cutioner's Song and 1993 Cable: Blood and Metal. For the entirety of his first series (1993-2000), he is said to be destined to fight against mutant supremacist Apocalypse, a tyrant during his future timeline. His purpose seemingly ends after Cyclops dies by merging with an aging Apocalypse in 2000 crossover Apocalypse: The Twelve. His lack of a mission or purpose is even acknowledged in-universe in Cable #79 (May, 2000).
4) Romulus (Wolverine's enemy) - after House of M (2005), Wolverine regains the memories of his past, which are explored in an arc in his solo title (Wolverine #36-40, 2006) and later in Wolverine: Origins (2006-2010). Throughout "Origins", it is hinted that Wolverine's entire life has been manipulated from the shadows by a mysterious character, which is later revealed to be Romulus. Romulus is defeated in the final arcs of "Origins", but later returns in an arc in Wolverine #310-313 (2012), and vanishes from the limelight into limbo.
I think many Time Travellers in comics are prone to fall in this trope.
The characters in question should be integral/vital/pivotal to the plot the writer is using them in. Sometimes, the character is so connected to that storyline that, when it folds, the character may survive it, but has no narrative purpose beyond their original appearance.
Edited by KHR-FolkMyth