To be the Lion and the Lamb depicts Jesus' power and strength and at the same time His humility. He is submissive on His way to the cross but comes out of the tomb victorious with resurrection power.
In His capacity as Beginning and End, He starts and finishes. He was at the creation and in the end "will draw all things to Himself".
Who would not be at ease in the presence of someone bearing such titles?
I know I will, because He's got me covered.