For in this world he loved no man so,
And he loved hym als tendrely agayn.
So wel they lovede, as olde bookes sayn,
That whan that oon was deed, soothly to telle,
His felawe wente and soughte hym doun in helle.

– Geoffrey Chaucer

The Canterbury Tales, The Knight’s Tale. The bond of love and friendship between Theseus and Perotheus runs very deep that they would follow each other to hell! And it is about to have an important impact on how the tale develops. It turns out Perotheus also knows and loves Arcite and he intercedes on his behalf with Theseus.