Warning: this list contain spoilers for anyone who has not watched the first 7 episode of Season 4.
Here is a quick and dirty guide to the names, faces, and backgrounds of all the characters you need to know.
Ygritte is a wildling from north of the Wall. When Jon Snow, Ned Stark’s bastard son and member of the Night’s Watch, was undercover with the wildlings, the two had a prolonged relationship that ended with her shooting multiple arrows into him. Now, Ygritte is part of Mance Rayder’s army preparing to attack the Night’s watch.
Walder Frey is the lord of the Twins, mighty bridges that connect the north with the rest of Westeros. He’s a crotchety old man with a dozen daughters and marries young women. To get revenge on Robb Stark for not marrying one of his daughters, Walder staged a massacre at one of his daughter’s weddings that ended in the murder of both Robb Stark and his mother Catelyn. This was called the “Red Wedding” and essentially ended the Stark’s rebellion to free the north from the rest of Westeros.
Varys is know as the “Master of Whispers.” He has informants all over the world and knows almost everything about everybody. Varys was born in the Free Cities across the Narrow Sea and was castrated there, a fact few people will let him forget.
Tywin Lannister is the grandfather and Hand of the King to Tommen, the newly-crowned boy king. That makes him the essential rules of Westeros. Tywin is also the lord of Casterly Rock, the Lannister’s wealthy ancestral home. He’s a stern man who gives great weight to power and money.
Olenna Tyrell, the old woman in the picture above, is the grandmother of Margaery Tyrell, the wife of the last king and the future wife of the new king. Olenna is also known as the “Queen of Thorns” because of her ability to bring about ruthless results through scheming and secrets.