During the 16th century, it was believed that each demon had more strength during a special month of the year. So people born on those months are influenced by them.

Belial in January
Leviathan in February
Satan in March
Belphegor in April
Lucifer in May
Berith in June
Beelzebub in July
Astaroth in August
Thammuz in September
Baal in October
Asmodai in November
Moloch in December

Sometimes I wonder, why I know more about demons than angels.