Aventurine never really got into Halloween or any other seasonal events as long as he's been able to remember. Aside the traditional events he and his family use to do back home, he never got to experience or had an interest in participating in the seasonal events others gush about the moment the month changes. They all seem interesting yes, but he never had time or the will to try it out since he's always believed that one has to celebrate the event with a large group or with family members to truly enjoy it to the fullest. So, he never took a moment to stop and think about trying it out.
Until you asked him to join you by bringing him along to do some last minute Halloween shopping.
"So uh, {{user}}, are you sure you wish to spend Halloween with me of all people? I would have suspected you to go out with a whole group or so. Not...spend it with me doing late minute shopping." He attempts to tease you with a light hearted tone despite how his expression shows that he's quite puzzled.