- "Eddin: I've always taken care of you, Lucan.
Lucan: Taken care of me? You're my kid brother and you take care of me? Did you ever think about that?! Huh?! Did you ever once think about that?! "
- ―Eddin and Lucan Blackgard
Lucan Blackgard is a recurring character in the fourth, fifth and sixth seasons. He is a son of Lord Trevyr Blackgard and his deceased wife, Lady Laenah Blackgard. He is the younger brother of Dyron Blackgard and older brother of Eddin Blackgard. He is married to Jenelyn Harrigon. He is considered a weakling among House Blackgard.
Lucan is the thirdborn son of Lord Trevyr Blackgard. Trevyr is the Lord of Ebonheart and Lord Defender of the Stormlands. Lucan is considered to be weak and unable to lead. He was kept out of most of House Blackgard's affairs and this frustrated him multiple times.
Trevyr sends Lucan to King's Landing to act as a representative of House Blackgard to the Crown. Lucan oversees all King's Landing activities that are involved with House Blackgard or The Borderlands. In an attempt to gain control of the Borderlands and gain House Blackgard as allies, Cersei Lannister offers Lucan a position on the Small Council, but he refuses, being able to see right through her. However, Lucan later reconsiders and accepts, using it as an opportunity to learn about Cersei's other activities. He is able to use his position to subtly block Cersei's attempts to gain a foothold in the Borderlands or within House Blackgard.
After Dyron Blackgard's death, Lucan receives word that his father, Trevyr Blackgard, has disinherited Lucan, refusing him to become the Lord of Ebonheart. Lucan, angered, stays in King's Landing and does not return to Blackgard to attend Dyron's funeral.
Lucan marries Jenelyn Harrigon. This strengthens House Blackgard's relationship with House Harrigon even more. Knowing that Lucan was considered the weakling and the most cowardly among lord Trevyr's sons, Jenelyn's father Lord Rickard had concerns about Jenelyn's safety, sending Ser Lannord and Lancen Storm with them on their way to King's Landing, where they remained with them until Ser Rolland Hollard takes care over Jenelyn. After a year of marriage, Jenelyn announced her pregnancy and that Lucan would become a father. This does nothing to reconcile Lord Trevyr and Lucan. Lord Trevyr does however right a letter directly to Jenelyn congratulating her. Jenelyn later gives birth to Mercyl, but yet again, it did nothing to reconcile him and his father.
When Cersei Lannister initiates the Destruction of the Great Sept of Baelor, Lucan is preparing to attend Cersei's trial when he is approached by Roman Mercer, who has newly returned to King's Landing. Lucan orders him to stand aside. However, Roman says that he can't do that and refuses to move. Realizing that Roman has come to kill him, Lucan casually grabs a candle holder and uses it to fight Roman. They both manage to disarm each other, but as Lucan runs to get his sword, Roman manages to stab him in the gut. After falling to the ground bleeding, Roman cruelly mocks Lucan, saying that he sent men to kill his wife and son as well. He leaves Lucan's room with the door open. As Lucan crawls out of his room to try and warn King Tommen, he dies of blood loss. His death initiates an open rebellion between the Iron Throne and House Blackgard, who have since openly declared to support to House Targaryen's bid for the Iron Throne.
Following the destruction of the Great Sept, Ser Lancen is almost beheaded, and Jenelyn is strangled to death by the members of the Blackwatch. Mercyl is smuggled out of King's Landing by Ser Rollan and Ser Lannord, and taken to Smithestone, and taken into the care of his bastard "uncle" Ser Ardrew Ashes.
Spoken by Lucan
- "Roman Mercer: Greetings, Lord Lucan.
Lucan Blackgard: Ser Roman....I thought you'd been banished from the city?
Roman Mercer: Oh, I was. But I've been invited back.
Lucan Blackgard: By who? Oh, it doesn't matter. Could you please stand aside? I'm needed at the Sept of Baelor for Cersei Lannister's trial.
[Lucan tries to move past Roman, but Roman blocks him.]
Roman Mercer: I'm afraid, Lord Lucan, that you won't be attending Cersei's trial.
Lucan Blackgard: What are you talking about? What's going on?!
Roman Mercer: A new order is rising, Blackgard. And I'm afraid you aren't a part of it.
Lucan Blackgard: You're....here to kill me?
Roman Mercer: (laughs) And people call you the idiot of House Blackgard! Looks like you're smarter than you look, Lord Lucan!
Lucan Blackgard: But, why?! What have I done to deserve this?!
Roman Mercer: Absolutely nothing. Trust me, my lord, it's nothing personal. It's just time for the old order to end.
[Roman pulls out his sword and slashes several times at Lucan. Lucan is able to dodge him and grabs and nearby candlestick and fight Roman with it.]
Roman Mercer: Stop acting foolish, Lord Lucan, and meet your Wolf God as a brave man.
[Lucan manages to knock Roman's sword out of his hand, but Roman also kicks aside the candlestick. Lucan punches Roman in the face before rushing over to get his own sword. However, once he turns around, Roman stabs him in the gut with a dagger. Lucan instantly falls onto the floor. Roman kneels beside him, laughing.
Roman Mercer: And don't worry about your wife and son. I sent some men after them too. With any luck, they're dead already.
Lucan Blackgard: No....
Roman Mercer: Give my regards to your father and brother."
- ―Lucan is confronted by Roman Mercer.
Spoken about Lucan
- "He was my brother. He may have been a fool but he was still my brother. I want retribution. I want revenge. No one will get away with this easy. I want the names of every person involved in this massacre. And I want their heads."
- ―Eddin Blackgard, furious over the death of his brother