According to the Daily Star (via UnrealityTV), poor Lottie was being harassed online by a guy sending tweets and texts, which included naked pics and inappropriate messages. Ugh.
Louis got the creeper's number and, the Daily Star reports, told him: "You're 24 and she is 15. What are you thinking? Don't even think about coming to the stadium tonight. I don't want to see you there."
An insider spilled: "Louis wanted to be focused on playing at one of the biggest venues in the country but his sister comes first and he wanted to make sure he was protecting her."