Visions and Propositions
Manawydan waits in shadow, biding his time, watching. I visualise him cloaked and hooded, looking as if over my shoulder, yet also withdrawn to a liminal space where a portal opens into the Otherworld.
Was he there when Rhiannon came? The tale* does not tell it, only that she came to claim Pwyll for a husband. Did Arawn watch from the other side?
Was one watching when her child was taken from the cradle by her side? Or when she waited by the horse-block for Pryderi to return?
The tale* tells that Pryderi, grown now, went to Ireland (or was that Annwn?) with Manawydan and his Brother Brân for the sake of their sister Branwen (but there was also a cauldron).
They returned with the head of Brân (just seven in all from a great army returned) and Branwen who broke her heart.
The Birds of Rhiannon sang to them then and time was still until the door – which Manawydan reminded them should not be opened – was opened; and they went to the White Mount to bury the head – Brân’s head – that had kept company with them when time did not flow.
Manawydan, alone now in Thisworld of the siblings of Llŷr, he who was “wise of counsel” as the Black Book has it**, took counsel from Pryderi to go to Dyfed and be with Rhiannon.
So they are wed but he watches Pryderi and then Rhiannon go through the enchanted fort into the Otherworld (he counsels caution – another door best not opened? – but will not hinder) and must wait for his chance to release them and restore the land.
So he waits until it is time to act. Then he acts. Like a gatekeeper opening and closing the Portal he watches – and enables – the coming and going of those who would pass and those for whom passing is a rite of passage.
-*-
Commentary
Consider the Triad, referred to in the Mabinogi, about the Three Golden (or noble) Shoemakers, one of whom is “Manawydan Son of Lludd” in one of the manuscripts of the Triads, though “Son of Llŷr“ in another. Rachel Bromwich says that this transference is common so that Llŷr & Lludd are interchangeable***. As Lludd is cognate with Nudd should we therefore regard Manawydan as the brother of Gwyn ap Nudd?
If Manawydan is a son of Nudd (Nodens), Brân and Branwen are also children of this god. By which perhaps we should understand ‘of his family’ or even perhaps ‘expressions of his nature’? Family relations between gods are never quite the same thing as those between people.
Beli Mawr is said to be the father of Lludd and Lleuelis****. But also in legendary history of Caswallawn (i.e. Cassivellaunus) leader of the Brythons who opposed Julius Caesar in his brief incursion into Britain in 54 bce. Many of the early kings of Wales traced their lineage back to Beli Mawr via Cunedda. Clearly here we are in territory where myth, legend and history merge and the difference between gods and ancestors is either confused or irrelevant, depending on your point of view.
But if Manawydan is an offspring (however understood) of Nudd, and shares an identity (however understood) with Gwyn, the identification of these two ‘sons’ of Nudd as Thisworld and Otherworld faces of a god, on either side of the portal, seems to cohere.
§
*‘The Tale’ here is the First and Third branches of The Mabinogi
** In the poem ‘Pa Wr yw’r Porthor?’ (Which one is the Gatekeeper?)
*** Trioedd Ynys Prydein (Third Edition, p. 419 & p.421)
**** In the medieval Welsh tale Cyfranc LLudd a Lleuelis
awenydd.cymru 
Interesting stuff. I’ve never met Llyr and have no sense of whether the claim he and Lludd are identical holds. However, I have been led by Will Parker into considering the notion that after Pwyll becomes Pen Annwn after the identity exchange with Arawn their identities remain mixed and that both Pwyll and Arawn are the father of Pryderi. And that’s why the Annuvian monster snatches him. If Arawn and Llwyd (who’s probably Brenin Llwyd) are also titles for Pen Annwn then that explains his second kidnapping too. If Gwyn is also a title of ‘the same’ figure then you add another layer of complexity – two otherworldly brothers contesting for Rhiannon – an otherworldly goddess -from either side of the veil…
I’ve had repeated affirmations over the years of Manawydan as a gatekeeper to the Otherworld. As one of Pryderi’s father figures, I wondered if he also fulfilled that role in the tale not just in watching Rhiannon and Pryderi go into the fort, and then bringing them back, but also as a presence for the other coming and goings where he is not, as a character in the tale, present? As far as the tale goes, of course not. But my intuition is that this is the case. I also wonder about the significance of the name of the territory of the Gododdin being ‘Manaw Gododdin’, far from ‘Ynys Manaw’ (Isle of Man). Evidence from the Gododdin poem suggests that Lugus was their patron god, but if Manawydan was the god of their territory this does raise other possibilities.
I came upon Manaw Gododdin again during my research on Maelgwn’s background. It certainly seems possible he was one of their patrons and a pan-Brythonic god prior to their Romanisation and Christianisation.