@iWantLautner: Magnus, what would you dress up as for Halloween and why?
-"Downworlders and Shadowhunters don't really dress up for Halloween. It's mundane."
@ericalynnRAWR: Jem: How do you feel about redheads.
-"I prefer girls with dark hair...."
@deetrishsan: Jace: do you ever wonder what Clary dreams about??
-"Me, I assume."
@RaquelOsuna: Jace, what was your best costume for Halloween?
-"Shadowhunters regard Halloween not as a holiday but as their busiest work day of the year."
@ShesGotTheRhytm: Jocelyn, with everything that happened is the wedding on hold?
@MissNerdyNicole: Can i ask Will how he was feeling at the end of CP?
-"At the very very very end? Startled. :)"
@kia_nolan: Jace: One of my friends thinks he's just like you would you consider going out with a mundane version of yourself?
-"I am straight. And taken. But you, know, otherwise..."
@ShesGotTheRhytm: Tessa, what qualities do you look for in a man?
-"Honesty, a good heart, a good soul. Someone who reads."
@ericalynnRAWR: Sebastian: So. With all the evil deeds and whatnot, have you ever had the time/inclination to have a steady girlfriend?
-Sebastian: "Have you MET me?"
@Mykheaton: Will when did you start being able to hear & see ghosts?
-"All Shadowhunters can if the ghosts feel like being heard. I can just hear them regardless. I can't recall since when. A long time."
@insummerland: Magnus: glitter or leather?
@TeamFreeWill: Jace: What's your biggest regret in your life?
-"Not killing Sebastian when I had the chance."
@GabyLafara: Magnus, if you could dress up Alec, what would you dress him as?
-"I like him the way he is, ratty jumpers and all."
@HEHinze: Jem: Have you ever considered exploring 'the other side of the tracks'?
-"The what, then?"
@KaienCross19: Clary: do you want to be taller?
-"Well, a few inches. That would be nice. But I think I'm done growing."
@munchkennina: Jem: WIll you ever get better???
-"Well... that would be nice. But I'm not counting on it."
@imeannothing: alec: what's your favorite thing about magnus?
-"He has a true heart."
@crystalc13: Will: if you met a person who was remarkably similar (in attitude) to you, what would you do?
@Jemxtessa: Jem: r u ever gonna tell Tessa what Ni hen piao liang really means?
-"If she seems inclined to know . . ."
@deSaintPierre_: sebastian: who do u despise more, clary or jace ?
-"Oh, I quite like them both."
@little_ewa: Tessa, do you think you could ever trust Nate again after what he did?
-“No, I don’t . . . I don’t think so.”
@kvcampanella: Jem, what were your first thoughts on Will?
-“He didn’t treat me any differently because I was ill.”
@liz_aleco: Jace do you ever think getting over Clary and found someone else?
@PolianaSepeda: Jace: How many children you and Clary want to have?
-“Jace: *chokes to death*”
@kvcampanella: Jem, what were your first thoughts on Tessa?
“Author says: there’s a whole short story on that in one of the CP editions!”
@adinanevarez: Clary, what do you thin your life would be like if you didn’t meet Jace?
-“Well, Valentine would have come for the Cup eventually. I don’t think a normal life would have been possible.”
@Luciiane: Simon, if you had to describe Isabelle in one word, what would it be?
@iWantLautner: Simon, who do you think has the best hair: Jace, Alec or Magnus?
-“I’m going to say Jace, because otherwise he’ll kill me.”
@insummerland: Sebastian, beside your evilness, redheads, blondes or brunettes?
-“Oh, yes please.”
@iWantLaunter: Simon, if Jace was a girl do you think you’d like him? 😀
@iaminpeaces: Jace, if you had a pet guinea pig, what would you name it?
@PwoperMuserMar: jace, what would you do if clary cheats on you?
-“Who would cheat on me?”
@Devereaux_Yvet : COFA SPOILER Lilith, you considered Sebastian to be your son. Does this mean you consider all warlocks to be your children in the same way?
-“No. Sebastian was different.”
@AmandhaNunes: Will, what’s the most important thing to you?
-“The promises I’ve made to others and myself.”
@PolianaSepeda: Jace: What would you think if Clary had an identical twin sister?
-“Kinda hot . . .”
@AboutEllie: Jace, do you smoke?
-“O_O No. I train too hard for that.”
@imeannothing: simon, what does sebastian’s blood tastes like?
@nobodyperfect15: Jordan do you still like Maia?
-“Yes. But I don’t think it’s mutual.”
@cantbefixed_: Jace, would you kill Simon if you could?
-“I saved his life, so, odd question…”
@Devereaux_Yvet: Clary, would you—like Juliet—stab yourself if Jace were to die in an unfortunate manner?
-“No. I would be brokenhearted but I think it dishonors someone’s memory to kill yourself over them.”
@Luciiane: Alec, Magnus has some curious habit that’s worth mentioning?
-“He likes to play the ukelele.”
@saghar_o_o: Jace: Why are you so incredibly hot?
-“It’s a blessing and a curse.”
@insummerland: Silent Brothers, isn’t to weird to be in silent all the time?
-“Silent Brothers: “
@Devereaux_Yvet: Isabelle, what is the longest period of time you have been in a relationship with someone?
-“About three weeks.”
@VictoriaDurm: Simon, why are you so sexy?
-“Ah- w-what? I, uh…”
@KyleWKerr: Magnus, as a place to live, do you prefer NYC or London?
-“When I get bored, I move on. So NYC.”
@PaoMtzP: charlotte: from where do you get the patince to handle will?
-“I ask the Angel that all the time.”
@monkeybymyself: Henry, how did you & your wife, Charlotte, meet?
-“At a Christmas dance.”
@cantbefixed_: Jocelyn, if you could change something about your past, anything, what would it be?
-“What WOULDN”T it be? I would have told Clary the truth from the beginning.”
@Freya_Mentalist: Luke, would you and Jocelyn ever consider having another child?
@ClaBrice: Robert, I’ve seen Maryse asked about Alec’s relationship with Magnus, I’m a little curious about your own feelings on it
-“It’s not what I would have wanted for my son.”
@AudriannaLF: agnus: What’s the sexiest thing about Alec?
-“He’s eighteen, he’s got a Stamina rune, what’s not to like?”
@saghar_o_o: Clary: Do you think you would have fallen for Simon eventually, if it weren’t for Jace?
@CyrusCandies: Is Sebastian as hot as Jace?
-“I would say yes. Different types. Also you have to ignore the evil.”
@kvcampanella: Isabelle, are you ever going to tell Alec about your father’s secret?
-“I hope I don’t ever have to.”
@Rebe_mx: jace: what are your plans for the future?
Source: Cassandra Clare’s Twitter