#ehhhh yeah

Step 1: Mentally acknowledge every aspect of the plot and character that needs to be delicately revealed and would put people off if placed in the summary. Split into sections and half-truths.

Step 2: Introduce character as Blank Slate. (Personality exists but is not yet fully apparent.)

Step 3: Give audience cause to accept character as Temporary Cast Member: Introduce mystery.

Step 4: Have Blank Slate Temporary Cast Member affect canon in a natural way with little to no consequence, introducing first hint or two as to the nature of character's future involvement.

Step 5: Bring attention away from character; create 40,000-ish word original episodic mini-arc plot for them to be involved in only as much as any other member of the cast.

Step 6: Note developing dynamic between character and Canon Cast Members. Acknowledge they are still New and Temporary in the eyes of Main Character.

Step 7: Repeat steps 4, 5, & 6 in various ways and various orders as seen fit until desired dynamic between character and Canon Cast is reached, all the while progressing canon plot as seen in source material with minor to major changes as naturally occurring through butterfly effect of character being present.

Step 8: After a recognition of the established dynamic, allow major canon event to disrupt said dynamic, causing character's position to become Temporary again.

Step 9: Emotionally introduce and re-introduce all Cast Members. Establish new dynamic over time.

Step 10: Reveal first Half-Truth. Allow audience to understand that there is more to learn without necessitating that any of it is a groundbreaking Big Reveal.

Step 11: Slowly establish new relationship character has with the universe at large within alternating versions and orders of steps 4-6.

Step 12: Major canon event reveals the other half of first Half-Truth. After initial reaction, prevent character and Canon Cast from explicitly processing this information via continuation of major event, allowing the audience to absorb Full Truth while previously established dynamics continue without immediate drastic change.

Step 13: Relevant cast members refuse to acknowledge the inevitability of a change in dynamic due to Full Truth.

Step 14: New Canon Cast Member appears. New dynamic is established without them being aware of Full Truth.

Step 15: Full Truth is revealed to New Canon Cast Member due to minor canon event; reveal functions as first true acknowledgement.

Step 16: Hugely Major Canon Event changes everything and Full Truth is finally accepted by Relevant Characters.

Step 17: Now that Full Truth of character's role in the plot and word is established and accepted, the rest of the nature of various related headcanons may be explored via similar but less mysterious and subtle means.