One possible reason could be that Percy has unspoken feelings for Annabeth. He might be in love with her but not yet ready to admit it, so he just stares, trying to figure out his emotions.
It could also be that Percy is simply in awe of Annabeth. She is very intelligent and strong. Her strategic thinking and combat skills might make Percy stare at her with admiration, like when she comes up with a brilliant plan to solve a problem in their adventures and Percy just stares at her, amazed by her capabilities.
Chapter 339, "Changes in Li Hu and Yang Zhong, the Hou Family's Opportunity, Giving Advice", is the clearest early answer because it turns Li Hu's situation into a concrete plot event. The chapter gives readers a real answer by opening on The third year of Great Xia, September 9th The former South District... and ending on Qingyuan Power can only enhance explosiveness by ten percent, but....
Chapter 136, "Jiang Li Can Actually Draw Talismans?!", is the clearest early answer because it turns Aunt Ying's situation into a concrete plot event. Early on, A few people retraced their steps back to the place they had just.... By the end, Aunt Ying and the camera PD arrived soon after..
Chapter 194, "Come and Exercise with Little Shang", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. Early on, Director Sun, this isn't another one of your production team's wicked....
Chapter 22, "Number 7203", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event. The chapter turns that into something concrete by moving from Hearing this, Su Yinwan looked at Shang Shaojing with a face full of...
Chapter 341, "Moao's Nine Towns, the Inspection System and Zhenyu, Li Hu and Hong Yuru", is the clearest early answer because it turns East Ridge's situation into a concrete plot event. Early on, The entire Moao Mountain Range stretches from northwest to southeast.. By the end, The powerful northern Three Towns block the north..
Chapter 20, "Miss Su, your defense is somewhat clumsy", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. It opens with Several people turned their heads upon hearing the sound and saw... and closes on So, he turned and questioned Jiang Li..
Chapter 41, "Actually Still the Museum Director?!", is the clearest early answer because it turns Dharma Teachings's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The live streaming room suddenly boiled over again.
Chapter 202, "Jiang Li Official Announcement?!", is the clearest early answer because it turns Daniu's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li couldn't believe it, "Just to take a picture?" "Yes, just to...
Chapter 518, "Calculator: 438", is the clearest early answer because it turns Miss Jiang's situation into a concrete plot event.
Chapter 158, "It's Time to Recruit Someone Who Understands Mysticism to Work Here", is the clearest early answer because it turns Sister Li's situation into a concrete plot event.