Describe adelines relationship with third brother

Third Brother is the youngest of the three brothers born out of Father's first marriage. While he is very close to his two older brothers and is involved in their hijinks, he is portrayed as exceptionally compassionate towards Adeline. Adeline loves her brother for this and often sees him as the most reliable of the bunch. However, she feels betrayed by his conspiracy in the urine-orange juice prank on the day Adeline won a major academic award. Although Third Brother is the closest to Adeline, their relationship is not exceptionally intimate.