As Merlin he is the teacher of Arthur, religious leader of the people, as Ambrosius he is the High King, martial leader of the people.

Arthur is the heir to both, natural son of neither.

In the Welsh triads Merlin is the guardian of the Thirteen Royal Treasures of the Isle of Britain and takes them to the glass tower for safe keeping. Merlin ( Myrddin) in early welsh poetry is repeatedly linked with apples and apple-trees. Merlin sleeps in or under an apple tree in the Caledon forest.

According to Geoffrey of Monmouth both Merlin / Ambrosius were involved in the construction of Stonehenge.

In the different legends a Flowering Hawthorn tree, an Oak, a rock and a glass island are all Merlin's prison

Merlin's Cave, Tintagel, Cornwall