 If the character is canonical but disliked, or if the character is original to your story, you need to do more work to make the audience care about the outcome.

Don't do it by laundry list.

Spend the time, spend the effort.  Show the character in his/her natural habitat.  Don't be afraid to show the character having a good time, instead of constantly wallowing in misery; trying to evoke pity is not a good way to get the audience on the character's side anyway.  Show the interactions between characters instead of telling the readers about the relationship.  Show the aftereffects of traumatic (and other) events by how the character acts later, show how s/he relates to people now and how that might be different from the way the other characters expect, and then let the character talk about it, instead of front-loading your story with summarized drama.  Let the character be funny or quirky or stolid or smarmy or quick or giving or all of the above, and let us see her/him doing it.  Don't tell us what the character is like, show us examples in your story so we think the same thing.  Don't tell us what happened, let us walk along that road too.  Let us experience the emotions the characters do instead of just hearing about them, let us revel in their victories and weep in their losses, and let us miss those characters long after we've finished the story.

And that's all I have to say about that.

In the ebb and flow of interaction with our favorite fannish source material, fans inevitably run into spaces in the canon where there are hard and fast answers, only clues.  Things that happen between episodes or books.  Off-screen antics implied but never actually stated.  Even actions and words that make it to the final print but can be interpreted in multiple ways.

If it happens on the series or on the page, it's canon.  If it happens on the screen or the page and is later retconned (retroactive continuity, or "we changed our minds later so it really happened this way") then it's annoying and convoluted canon, and can be ignored or not at your own discretion.

If the show's headrunner, or the episode's writer, or the book's author says, "This is what I intended for this to say," it's authorial intent.  Authorial intent is not canon.  No, really.  When J.K. Rowling announced after the publication of "Deathly Hallows" that Dumbledore was gay, that did not make it canon.  That made it authorial intent, subject to be accepted or not by the fans of the series.  Why is this?  Because authors change their damned minds.  Because networks hand down edicts.  Because actors get pregnant or arrested on DUIs or die.  *moment of silence for John Spencer*  Because cancellation threats mean wrapping up storylines faster than originally intended. 