If they talk to themselves,laugh when nobody is around and they do not have the TV on or are laughing when they do not have their smartphone nearby.Also crying a lot for no reason.If they say that they hear voices when nobody is around.If they do things that do not make any sense.Maybe they need to talk to someone such as a friend as they could be going through a tough time. If someone did have a talk with the person and things did not get any better, maybe professional help is needed.
B.
And maybe put your question in the English/Literature tag next time lol
