Lucifer felt a bit replaced. It added to the discontent he would later feel, but right now he didn't begrudge Uriel. Uriel had the one sun to keep an eye on, while Lucifer's job was to make light everywhere. He'd even created the one Uriel kept watch over, but didn't mind giving it over. He was plenty busy.
But when he spotted his brother and noticed the confused look he titled his head. Curiously he went closer until he was next to Uriel. Like him the light and heat didn't bother him and he smiled to the Sun. It was like seeing an old friend, and he brushed his finger's along it's essence in greeting.
Then he looked at Uriel, "Something is bothering you. Is everything alright?" Uriel knew how to handle the sun, unlike Satan, and he didn't detect anything wrong with it's form so he wasn't too worried.