dzzthink: This angel is characteristically striped like a zebra, and noticeably more black than white, casting an ominous shadow across the sun-lit Tokyo-3 city. This coloring seems to refer to the psychology concept for "splitting" or "black and white thinking", which is also referenced in the second title of the episode "splitting of the breast". This is a central theme of the episode as Shinji's seeming confidence at the start of the episode, and acknowledgment of his positive qualities, are quite literally enveloped by the negative experiences in his life as he is analyzed by Leliel.
UrsusArctos: As we'll discover later, the striped sphere is actually the Angel's shadow, with the Angel's actual body being the shadow on the ground. Your explanation for the choice of the black and white coloration is fantastic, and fits the theme of the episode perfectly. It also marks how Episode 16 is a sort of transition from the lighter side of Evangelion (everything from Episode 08 to this episode) to the dark final third of the show where all the characters negative experiences come out. As an aside, the Nadia fan site thesecretofbluewater.com had a memorable but absolutely ridiculous theory linking Leliel's Zebra-like appearance with the absence of Zebras in Nadia.
