**Core Concept**
Induced psychotic disorder, also known as folie à deux, is a rare psychiatric condition where one person's psychotic symptoms are induced by their close relationship with another person who has a similar psychotic disorder. This condition highlights the complex interplay between social influence, suggestion, and the development of psychotic symptoms.

**Why the Correct Answer is Right**
The characteristic symptom in induced psychotic disorder is the acceptance of delusions by one person, often referred to as the "induced" individual, based on the delusions of the other person, known as the "primary" individual. This acceptance is a crucial aspect of the disorder, as it demonstrates the significant impact of social influence on the development of psychotic symptoms. The induced individual may not have any pre-existing psychotic tendencies but will adopt the delusions of the primary individual, often due to a close and intense relationship.

**Why Each Wrong Option is Incorrect**
**Option A:** Insomnia is not a characteristic symptom of induced psychotic disorder. While sleep disturbances can occur in various psychiatric conditions, insomnia is not a specific or defining feature of this disorder.
**Option B:** Profound mood disturbance is a common feature of many psychiatric conditions, including mood disorders, but it is not a characteristic symptom of induced psychotic disorder. The primary symptom of induced psychotic disorder is the adoption of delusions, not a mood disturbance.
**Option D:** Suicidal ideation can occur in various psychiatric conditions, including psychotic disorders, but it is not a characteristic symptom of induced psychotic disorder. While suicidal ideation is a serious concern in many psychiatric conditions, it is not a specific feature of induced psychotic disorder.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that induced psychotic disorder can occur in any close relationship, including romantic partners, family members, or even friends. The key factor is the intense social influence and suggestion that leads to the adoption of delusions by one person.

**✓ Correct Answer: C. Accepting delusions of other person**