Faites vos jeux!, as they say at the roulette wheel. An enchanter and an enchantress, both rising like meteors, portray brothers who are rivals in love. She’s Emily D’Angelo, mezzo-soprano, as Xerxes (Serse), king of Persia; he’s Jakub Józef Orliński, countertenor, as Arsamene, a prince. Handel being Handel, the roles make equal demands on a singer’s artistry, imagination, and technique. —M.G.