Manny Heffley is Greg's spoiled little brother who gets anything and everything he wants and makes Greg jealous. Manny makes Greg jealous because he has rights Greg didn't when he was Manny's age such as being allowed to bring toys to church. Manny does lots of things to annoy Greg  but Frank and Susan never punish him no matter how much he deserves it. This happened when Manny drew a self-portrait on Greg's bedroom door in permanent marker. Greg thought Frank and Susan would be very mad, but he was wrong, infact,they loved it. Manny calls Greg "Bubby" which bothers Greg because he doesn't want his friends hearing it. Manny wasn't potty trained until October in book 2, so that is when he had to start preschool then unlike his other classmates who started in September. Unfortunately, now he's afraid of them because they were having their Halloween party and everyone was wearing their costumes. He is considered a spoiled selfish 4 year old preschooler who doesn't share his toys and throws temper tantrums which easily manipulate Greg's parents.