2 Sam 22:19-51--1 Kings 7

The transition from King David to King Solomon was met with some  low key "Absolom  vibes from his brother Adonijah". He knew Solomon was supposed to be King yet schemed to try to get to the throne first.

Even though Solomon spared him his life , Adonijah continued to scheme to build power to take over the throne for himself  by asking Solomon mother  Bathesheba to ask the King for Abishag to be his wife.

I think he forgot that King Solomon was full of wisdom. He saw all through  Adonijah scheme. He was still plotting to take the throne.  This plot caused his own demise.  

Lesson it doesnt pay to be deceitful, and don't take mercy for granted.