House Baelish is a noble house originally from the Vale. The seat of House Baelish was located on the Fingers in that kingdom, but they became Lord Paramounts of the Riverlands, ruling from Harrenhal, after the War of Five Kings. They lost their seat in the Riverlands during the war of the Ascent of the Lion, and the only living member is Alicent.
Seat: The Fingers
The original seat of House Baelish is an unnamed, old flint tower which commands no more than a few stony acres on the smallest of the Fingers. House Baelish's smallfolk consists of a village of a dozen families in huts of piled stone beside a peat bog. This tower and its surrounding lands are now controlled by House Baelish of the Fingers.
Former Seat: Harrenhal
The castle has five towers of dizzying size, with equally monstrous curtain walls. The walls are incredibly thick and its rooms are built on a scale that would be more comfortable for giants than humans. The castle's holdings are some of the richest in Westeros, claiming vast tracts of green fertile land.
Harrenhal covers three times as much ground as Winterfell and its buildings are so much larger that they can scarcely be compared. Its stables can house a thousand horses, its godswood covers twenty acres, and its kitchens are as large as Winterfell's Great Hall. When it was built it could have potentially garrisoned a million men.
Prior to the First Era
The current lord Emmon Baelish was born the second son of the reigning Lord Paramount of the Riverlands, and was second in line behind his brother Petyr Baelish before Petyr's death along with his father in separate incidents allowed Emmon to inherit Harrenhal. It is correctly rumored throughout the realm that Emmon murdered his father and brother to gain his seat, but is known widely throughout the Baelish family that Emmon was the one who murdered his kin.
Infinitely more ambitious than the rest of his family and an admirer of his ancestor Petyr Baelish's skill at intrigue and accumulating power, Emmon saught to increasee his house's stature immensely. His cousin Marq was always wary of his cousin's plots and believes he will ruin the family with his overreaching, though he shrewdly remains close to his lordly cousin as his best chance to fill his seat.
Immediately before the events of the First Era, Emmon's sister confronted him about murdering his family, to which Emmon had her put under constant watch. He shortly after began desiring the Vale of Arryn, whose claim was validated by his mother, Sansa Arryn.
The Baelishes held a tourney at Harrenhal that was attended by most of the important figures of the realm, including the current Lord of the Vale James Arryn. Rymar Royce encouraged Emmon to take action immediately, and it was during this same tourney that Emmon poisoned Arryn.
Ascent of the Lion
The Baelishes were relatively inactive during the beginning of the war outside of fortifying their own lands and keep. Lord Varyo Velaryon took this inaction as a sign of rebellion and took a large company of sellswords to begin terrorizing the Riverlands, burning numerous towns and holdfasts while slaughtering hundreds. Lord Randyll Frey of the Twins saw an opportunity to gain power in the Riverlands and laid siege to the castle with three thousand men when Emmon did not immediately bend the knee to the new Lannister king, Frey's own cousin Damon. Randyll himself was taken captive during the siege and kept in the dungeons of Harrenhal for most of the war.
During the same siege, Marq turned against his cousin and imprisoned him briefly, before expelling Emmon from the castle into the waiting army's arms, proclaiming he was responsible for murdering James Arryn. Proclaiming his fealty to the Lannisters, the new lord Marq Baelish took control of the Riverlands. Emmon was subsequently carted off the Vale to face trial.
Despite Marq's proclamation of fealty, he failed to heed the king's command and provide troops for the upcoming Battle of the Kingswood against the remaining forces of Harys Baratheon, leading to the events that would end the reign of House Baelish.
After the war ended, Nathaniel Arryn had Emmon executed for the murder of his brother James. Seeing Marq's lack of obedience in withholding his troops from the Kingswood as treason, King Damon sent his cousin Lord Aeron Greyjoy to pillage the Riverlands a second time with his ironborn. Lord Baelish kept his armies inside Harrenhal instead of coming to the aid of his vassals, causing him to lose critical support and the loyalty he needed. The armies of the Usurper besieged Harrenhal again, with Marq delaying certain execution for himself and his cousin Alicent by offering to release the still captive Randyll Frey in exchange for a pardon. However, Lord Frey was later mysteriously killed in the castle's dungeons (actually stabbed by his bastard son Gregor Rivers) and the full wrath of the Lannisters descended on the keep leading Sansa Baelish to flee the castle and be presumed dead by the realm. Meanwhile, Marq Baelish had enough time to escape with his cousin Alicent, living on in the Riverlands as a bandit.
Following House Baelish's downfall, Lord Edwin Frey was appointed the new Lord Paramount of the Riverlands while Randyll's son Brynden ascended to Lordship of the Twins, ironically fulfilling Randyll's desire to increase the power of House Frey.
Following Marq's escape, him and his cousin roamed the Riverlands for months, attempting to rally support. However, it all proved for naught when Lord Edwin Frey captured Marq, his cousin Alicent escaping to Lannisport shortly after.
With House Baelish exiled and thought extinct, Alicent Baelish made a name for herself in Lannisport as a painter, but was revealed after a visit by the King and Queen, where she was bid to wed Brynden Frey to consolidate his rule. Upon the last week before their wedding, Alicent's mother, Sansa Arryn was revealed to be alive, hidden under the care of Walder Bracken.
Sansa Arryn passes away culminating in the slaughter of Frey bannermen at her wake in Harrenhal by House Bracken. An act that garners notoriety by being called the 'Red Funeral'. This was the first step in the beginning of an open rebellion against Brynden Frey, Lord Paramount of the Riverlands, and a rise in support for Alicent Baelish.
Alicent's lover, Walder Bracken, names Alicent Lady of Harrenhal and prepares for siege against the approaching conflict with Brynden Frey's forces.
Robert Baelish, deceased
Sansa Arryn, deceased
Petyr Baelish, deceased
Emmon Baelish, deceased
Marq Baelish, deceased