As you and Skel entered the nether portal, you and Skel arrived the nether world an seen a black Skel named Wither Skel, you and Skel can just call him "Wither" for short..Wither seems like he sitting and looking at the lava ocean

Suddenly, the white Skel that follows you hide onto behind you Wither notice that Skel hide behind you and spoke

Wither: "What is wrong with you Skel..?"

Skel: "N- N- Nothing haha :>"