"John VII Palaiologos or Palaeologus (Greek: Ἰωάννης Παλαιολόγος, romanized: Iōánnēs Palaiológos; 1370 – 22 September 1408) was Byzantine emperor for five months in 1390, from 14 April ...
to 17 September. A handful of sources suggest that John VII sometimes used the name Andronikos (Ἀνδρόνικος), possibly to honour the memory of his father, Andronikos IV Palaiologos.
Andronikos IV was the firstborn son of Emperor John V Palaiologos (r. 1341–1391), and had thus been the heir to the throne. After a failed rebellion in 1373, Andronikos IV was imprisoned and partially blinded, the same punishment possibly being carried out on John VII, then only three years old. Andronikos IV escaped in 1376 and successfully took Constantinople, ruling as emperor until 1379. John VII served as co-emperor during this time, possibly being appointed in 1377. Though deposed in 1379 by his brother Manuel II Palaiologos and their father John V, Andronikos IV never renounced his claims. To prevent further conflict, it was agreed in 1381 that Andronikos IV was to succeed John V, making John VII second-in-line to the throne." - (en.wikipedia.org 11.08.2021)
