CREATE TABLE table_203_293 (id DECIMAL, "years of appearance" TEXT, "title" TEXT, "network" TEXT, "character name" TEXT, "actor" TEXT, "notes" TEXT)

who was the last character on bbc to be hiv positive ?
SELECT "character name" FROM table_203_293 WHERE "network" = 'bbc' ORDER BY "years of appearance" DESC LIMIT 1
SELECT "character name" FROM "table_203_293" WHERE "network" = 'bbc' ORDER BY "years of appearance" DESC NULLS LAST LIMIT 1