To make up, he agreed to swap places and faces with Arawn for a year and a day, in order to kill Arawn's fairy foe Hafgan. This they did, Pwyll virtuously keeping his hands off Arawn's wife in bed for 366 nights until slaying Hafgan at the ford with the single blow necessitated by Hafgan's magic. They then met again at Glyn Cuch and resumed their proper identities.
Arawn was impressed to find his wife still un-rogered, and Pwyll to find his kingdom in a period of sustained economic growth, so they remained friends and Pwyll became known as The King Of Annwn.
At the wedding Pwyll got overexcited and when a mysterious stranger asked for a boon, said "name it". He turned out be Rhiannon's unwelcome suitor Gwawl ap (son of) Clud, and he asked for her hand in marriage and the feast in another year. Pwyll had screwed up and was forced to agree, but Rhiannon had a cunning plan.
Meanwhile Teyrnon Twryf Liant, Lord of Gwent Is-Coed, decided to finally learn how his prize mare's foals were vanishing every May-eve. During his vigil he hacked off a huge claw that came through the window, and found a boy swaddled in silk, whom he raised as Gwri Golden-hair, and gave him the foal.
When he was four Teyrnon saw his similarity to Pwyll and made the connection, and returned him to his parents who renamed him Pryderi and fostered him out to Pendaran Dyfed.
When Pwyll died Pryderi ruled Dyfed and married Cigfa.
The two hosts met at Aberffraw and Matholwch and Branwen were wed, but the next day Efnisien mutilated Matholwch's horses out of spite and Matholwch left in a huff. Bendigeidfran sweetened him again with new horses and treasure, so he stayed, and then further with with a magical cauldron able to bring the dead back to life.
(Matholwch was once approached in Ireland by a giant Llasar Llaes Gyfnewid bearing a cauldron on his back, and his gianter wife Cymidei Cymeinfoll, who bore a fully armoured warrior every six weeks. After a year they became so unpopular that Matholwch lured the whole family into a specially made iron house, sealed it, covered it with charcoal and made it white-hot with bellows. Only the giant and his wife escaped to Britain, where they gave the cauldron to Bendigeidfran and settled peacefully.)
Matholwch returned to Ireland with Branwen where she bore him a son Gwern, but shit-stirrers in his court nagged him to take vengeance for his horses, by sending Branwen to the kitchens for a regular beating (one of The Three Unhappy Blows) and imprisoning everyone from Wales to keep it secret.
The Irish shit themselves, retreated beyond the impassable River Llinon (Shannon or Liffey) and destroyed the bridge. Bendigeidfran said "He who is chief, let him be a bridge", and his armies crossed over his back. Matholwch immediately offered the kingship of Ireland to Bendigeidfran's nephew Gwern, but he held out for the kingship for himself.
The Irish then built a special house to contain the enormous Bendigeidfran, and hid 200 men in bags hanging from its pillars, but Efnisien casually crushed their skulls through the hides. Then they made peace at the feast, but Efnisien threw Gwern into the fire and started a war. When he saw naked Irishmen throwing their dead comrades into the cauldron to revive them he hid amongst the enemies' bodies, and when he was mistakenly thrown in he burst it from within, and his heart also.
Bendigeidfran died from a poisoned spear, but commanded his seven survivors (Pryderi of Dyfed, Manawydan, Glifieu ap Taran, Taliesin, Ynawg, Gruddieu ap Muriel and Heilyn) to cut off his head and carry it round Britain for 87 years before burying it on The White Mount over London facing France.
When the seven returned to Britain to do the head's bidding Branwen died of grief, and only five pregnant women were left alive in all Ireland, so the British won by two and a head.
They learned that meanwhile Cradawg had died of shock at not seeing his uncle Caswallawn ap Beli (Manawydan's cousin) slay six of the seven knights left in charge using a mantle of invisibility, and only young Pendaran Dyfed had escaped into the forest.
Then they buried the head as specified (one of The Three Happy Concealements) to protect Britain from plague (presumably until one of The Three Unhappy Disclosures allowed the great plague to cross the channel in 1348).
After another year there whilst out hunting one day a huge white boar led the two blokes to a mysterious fort, but when Pryderi entered to retrieve his dogs he got stuck to a golden bowl hanging from iron chains attached to sky-hooks, and Manawydan lost his bottle and returned home. After chiding him Rhianon went looking for her son and became trapped the same, whereupon the fort vanished with them.
After promising Cigfa no sexual harrassment Manawyden took her to England again for another year where he cobbled, until again being driven back to Dyfed with a burden of wheat which he planted in three crofts.
For her safe return Llwyd promised to reverse all his enchantments, re-populate Dyfed, free Pryderi and his mum and take no vengeance. And that was the end of that.
Unfortunately Gilfaethwy fancied Gowein, and with his brother hatched a plot. They visited Pryderi disguised as two of twelve bards and persuaded him to lend them his magical hogs from Annwn in return for twelve horses, hounds and shields created temporarily from Gwydion's magic. By the time they were home in Gwynedd the spell had worn off and Pryderi was in persuit with an army and Math was on his way to meet him. With Math out of the way Gwydion entered Caer Dathyl and ravished Gowein before returning for the battle at Maenawrs Bennardd and Coed Alun, where Pryderi was forced to retreat. He then challenged Gwydion to single combat and was killed, and buried at Maen Tyriawg.
When Math returned home Gowein told him of her ravishment by Gilfaethwy, and as punishment Math used his own magic to turn Gwydion and his brother into stags, boars and wolves of alternating opposite sexes for a year each, and thus they spent three years in the forest mounting each other and between them giving birth to one faun, piglet and wolf-cub, which Math turned into humans called Bleiddwn, Hyddwn & Hychdwn Hir. The brothers were then forgiven.
When Gwydion introduced the four-year-old to his embarassed mum Aranrhod she cursed him to have no name but one given by her, so Gwydion used his magic to disguise himself and the lad as cobblers. The disguised boy was fitting his mum with shoes at Caer Aranrhod when he slinged a passing wren, and she remarked on his deft hand, unwittingly naming him Lleu Llaw Gyffes (Fair Hand Deft).
Utterly pissed off, she then cursed him to never bear arms until equipped by herself. So this time Gwydion disguised themselves both as bards to enter her castle and created an illusory fleet attacking them. In panic Aranrhod provided them both with weapons, unwittingly arming her son herself. Foiled again!
Her final curse was that Lleu should never have a wife "of the race that is now on this earth", so Gwydion and Math together used their magic to create a woman out of flowers, and named her Blodeuedd. Lleu married her and moved to Cantref Dinoding where he ruled from Mur Castell in the uplands of Ardudwy.
Gronw secretly made the spear and Blodeuedd somehow persuaded Lleu to give a demonstration by the River Cynfael, during which Gronw popped up from behind Bryn Cyfergyr and speared him through. Lleu screamed horribly and flew off as an eagle, and Gronw took his lands.
When Math heard of all this he searched all Powys for the transformed Lleu, finally persuing the speeding sow of a swineherd in Maenawr Bennardd in Arfon to a valley (now called Nantlleu) where he saw her feeding off rotting flesh and maggots falling from a putrid eagle in a tree. He sang it down and with his wand transformed it back into a ravaged Lleu, whom he took home to Caer Dathyl and healed.
Lleu subdued his lands a second time and ruled them prosperously, and later Gwynedd also. And was presumably either very frustrated or found an alternative to women.
Ready for books 5 to 8 ?