After Rob's death, Heather shows up at his funeral specifically to taunt and torment his friends and family with slanderous lies and uncomfortable truths. Heather takes particular delight in making his little sister Becky absolutely miserable, claiming that it was all Becky's fault her big brother died.
Several people at Rob's funeral have unkind things to say about him, possibly even his close relatives.
Rob actually did seriously wrong Heather in the past — though the crime may only be one in Heather's eyes — and she isn't willing to let it slide simply because he's no longer around to defend himself.
Enforced: The producers know someone needs to call out Rob for the problems he's caused in the past, but now that he's dead, only Heather is uncouth enough to do it.
Lampshaded: "What's he gonna do? He's dead, and good riddance."
Invoked: Heather's friend Meg brings up Rob's recent death and comments about how everyone's talking about what a great guy he was now, subtly goading her into reacting.
Exploited: Meg deliberately baits Heather into talking shit about Rob in order to turn others against her and make them see Heather as nothing more than a petty Jerkass.
Heather is not allowed to his funeral because she's probably going to make a scene (for another variation of this, see Averted #1).
After drinking a Truth Serum, Heather is asked about Rob and how awesome of a guy he was. So she decides to say nothing instead, reasoning that "If you have nothing nice to say, say nothing at all."
Jason keeps interrupting Heather, every time she's about to insult Rob (or at the very least, every time he thinks she's about to insult him).
Rob makes Heather sign a contract that reads "You're not allowed to make fun of me while I'm dead."
Discussed: Charlie and Eve notice Heather come in. "I bet she's going to go up and rant about him in front of everyone."
Deconstructed: Heather has a complex emotional history with Rob, and with his death, feels as though it will never be resolved to her satisfaction. Due to this, she can't bring herself to stay silent and listen to everyone whitewash his flaws, and she lashes out with such venom that people are disgusted with her 'overreacting' and being needlessly dramatic to draw attention to herself.
Reconstructed: Rob had been a flawed (or outright terrible) person not just to Heather, but to everyone. By breaking the social code to draw attention to his flaws, Heather points out the Elephant in the Room and people realize she's right.
Played For Laughs:
Heather shows up at the funeral to poke fun, but every time she opens her mouth, she receives an Offhand Backhand.
At Rob's request, Heather makes fun of him at his funeral in order to lighten the mood.
Rob's funeral is a big roast with everyone cracking jokes (that range from So Unfunny It's Funny to intentionally funny) at his expense.
Played For Drama:
Losing her beloved brother has pushed Becky to the brink of the Despair Event Horizon. As she struggles to wrap her mind around the fact he won't be there for her anymore, Heather shows up to rub salt into the wound.
Heather knows that Rob drove her family to bankruptcy with his business practices, but now that he's dead, everyone ignores her when she tries to talk about it.