ONE day Finn
  was hunting, and Bran went following after a fawn. And they were coming
  towards Finn, and the fawn called out, and it said: "If I go into the sea
  below I will never come back again; and if I go up into the air above me, it
  will not save me from Bran." For Bran would overtake the wild geese, she
  was that swift.
  "Go out through my legs," said
  Finn then. So the fawn did that, and Bran followed her; and as Bran went under
  him, Finn squeezed his two knees on her, that she died on the moment.
  And there was great grief on him after
  that, and he cried tears down the same as he did when Osgar
  died.
  And some said it was Finn’s mother the
  fawn was, and that it was to save his mother he killed Bran. But that is not
  likely, for his mother was beautiful Muirne,
  daughter of Tadg, son of Nuada
  of the Tuatha de Danaan,
  and it was never heard that she was changed into a fawn. It is more likely it
  was Oisin’s
  mother was in it.
  But some say Bran and Sceolan are still
  seen to start at night out of the thicket on the hill of Almhuin.