Mace Tyrell
Lord of Highgarden and Warden of the South, a genial, self-important man who commands the realm's richest lands and does mostly what his mother tells him.
A soul of House Tyrell, born at Highgarden.
The fuller tale
Season Three
Lord of Highgarden, and considerably easier to read than his mother — a broad, genial man who says the quiet part out loud about a marriage alliance everyone else is being subtle about. He arrives in King's Landing to finalize Margaery's match to Joffrey, delighted by the idea of a Tyrell queen and apparently untroubled by what kind of king Joffrey is. He talks trade and gold with Tywin, foots bills the crown cannot cover, and generally serves as proof that House Tyrell's wealth, rather than its wits, is what bought this family a seat at the table — the wits, everyone in the room understands, belong to Olenna.
Season Four
Present for Joffrey's wedding as the beaming father of the bride, more invested in the spectacle than in the groom, and just as blindsided as everyone else when Joffrey dies mid-toast. The match he spent a year building collapses in front of him, and he pivots without much visible grief toward the obvious replacement — Tommen is younger, more pliable, and still a king, and a Tyrell-Lannister wedding is a Tyrell-Lannister wedding whichever brother is standing at the altar. Mace's contribution to the family's schemes, as ever, is money and enthusiasm rather than subtlety, and he leaves the plotting to his mother and daughter without seeming to notice he has been sidelined.
Season Five
Cersei, tired of Tyrell money and Tyrell leverage cluttering up her court, finds an elegant way to remove Mace from the board entirely: she sends him to Braavos to negotiate with the Iron Bank, a task that sounds prestigious and keeps him thousands of miles from King's Landing while she goes to work on his children. Mace accepts the honor happily, entirely missing that it is an exile dressed up as an errand, and spends the season at sea and in foreign counting-houses while Margaery is arrested and Loras is thrown in a cell back home.
Season Six
Mace returns to a King's Landing he barely recognizes — his son mutilated and cowed, his daughter humiliated in the street, his mother furious and sidelined, and the crown he helped buy now openly hostile to his family. He has no plan beyond standing near his children as they face the Faith's judgment, which is the only role left to him by this point. He is among the nobles and Tyrells gathered at the Sept of Baelor for Loras and Cersei's trial, and when the wildfire takes the building down around them, Mace goes with it — no scene, no last word, just one more name added to a very long list that day.
How it ends for them
On the screen. Died when the sept burned (S6·E10)
The amiable Lord of Highgarden followed his children into the Great Sept for Loras's trial and died with them in Cersei's green fire, the last Lord Tyrell of the old line.
In the show he dies as he lived: adjacent to the point. Summoned to the Great Sept of Baelor for Loras's trial before the Faith, Mace stands in the crowd as his son confesses and is mutilated, visibly grasping, one beat behind everyone, that something is wrong — Margaery has read Cersei's absence correctly and is trying to empty the building. The High Sparrow's certainty holds the doors, and the wildfire cached beneath the sept takes the congregation whole: Mace, his daughter, his son, the Faith's leadership, and the future of House Tyrell in a single green bloom over the city. He is alive in the published books, at the head of an army, with no idea what the show has planned for the ground beneath the sept.
Their chapters, book by book
Where the page and the screen part
Book Mace is less buffoon and more blowhard-with-leverage: the books keep him permanently camped between the reader and the throne — angling for the Handship, promoting his cronies, besieging Storm's End again — and the realm's regents fear his army even while the story mocks his judgment. His Ashford 'victory' and the year of feasting outside Storm's End are book details the show never states. The show, needing a comic register for the Tyrell scenes, pushed him further toward farce — the Braavos singing, the wardrobe — and then gave him an ending; in the published books Mace is alive outside King's Landing with the Reach's power at his back and both his children in the Faith's hands, a situation with considerably more gunpowder in it than his show fate allowed.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.