Adding all these to the fact that he wasn't that mature before that... it is safe to say in the point where DMC5 happened, Vergil couldn't be more mature than an immature 20 years old at the physical age of 40, making him mentally 20.

“Who said you could speak, snake?”

“̴̗̪̦̋T̶̪͎̀h̷̖͍̊a̵̰̩͔̍t̵̘͖͖̂̽̽’̵̗̄̋̈́s̶̛̝̮ ̶̨̢̒̒t̵̢̰͗͆ͅh̷̭͉̠͊́é̸̙̤͈ ̴͈͖̜̏͑ȅ̶̘̗̫n̵͉̓̚d̷͓̮͔̉́̊ ̶̬̓o̶̡̊͘f̷̺̗̔ ̴̘̐̔t̷͔͋͌ḩ̴̙̱̑̿e̴̛̪ ̵̝̲̗͒̐͝s̸͔̫̣̈͛t̵̢͕̖̅o̵̠̊͠r̴̗̕y̶̨͚͍͗̔͝.̶̲̪̍̾͝”̴̨͌̽̕ͅ ̴̢̹̖̔͠ ̴̤̗͎͐̉“̸͕̜̬̾̓I̵̟̦͌ ̵͉͋̍d̷̼̉o̷͉̩͔͒̄͗n̴̞͋̄͝’̷͙͉͉̑t̷͇͔̠̃͑̓ ̵̦̃̿l̷̨̡̼͗͑̈́i̶̹̭̅̑k̷̥̮͘e̵̪̐ ̶̖̝̳̉t̷̙͚͚̽̀h̵̺͓̲́̈́͗á̷̧̛͝t̷͖̾ ̷̳̒ě̵̝̩̎̽n̴̰̾d̷͈͔̿͐ĩ̴̱n̴̳̦̖̈́͊g̴̪͝.̷͔̘̳̒̈́̾.̵̟̥̊.̶̇͑ͅ”̸͓̿̇ ̶̩͙̽͑́ ̸̩͑“̷̦̔W̴̛̩̬͐h̴̟̽̀͜ͅỳ̸̨?̴͇̹̣͗̽ ̵͔͔̃̇̊T̶̮͝h̵̙̲̼͝e̷̮̝͚̿ ̸̼͈̿͌̈p̴̗̜͈̂͆̓r̴͙͎̫̂i̶̱̲̒̍̚n̴̻̖̈́́͂ç̵̯͊ẻ̷̥̕s̴̪̹͆͐̚s̸̖͕̓͆ ̸̡̝̺͂ẁ̶̹̱͑̕a̴̙͗͌̚ṧ̵̥ ̴̗̖͊͜ṡ̷̨̘̝ạ̷͔̀̚̚v̷̛̪͍é̶̩͖͆͜d̴̢̠̓̀.̴̝̩̚”̸̡̟̱̋ ̸̭̯̒̕͝ ̸͕̯̟͠“̷̙͇͐͠Ṯ̵̪̻͌h̶̡̯̰̾ẹ̸̞͋͝ ̵̘̅p̸̤̿͆r̶̠̳̱̽i̶̻͋̋͘n̵͉͙͊̑͌c̸͙͇͎̉ê̵̬ ̶͙̭̄̃̕ẅ̷̭̫̤́a̷̾͌͑ͅs̵̯̺̼̍̇̅ ̷̙̠̈́́s̸̛͇͙͉̑͆ẻ̸̝̲̆ĺ̷̳̉͗f̷̲͇̌͌į̸̲͕́̀s̴͙̲̒h̸̜̼̏ ̴̪͈̎͌a̴̟̘̖̒͛̊n̶̢̤͝d̴͍́̾̕ ̸̠͉̮͋c̵̢͍̆̅r̴̥͎̓͌u̷̻̤̯̒͝ě̷͉͠l̶̝̣̜͋.̴̧̣̔̆͝ ̴͔̌T̵̟͇̜̋͝h̸̨͎̾ẻ̸̡̫͓̊ ̴̥̙̪̃̏̆p̵͓̦͒r̵̲̰̖̿͘͝i̸͈̋n̵͚̣̅̌c̷͙̀͑̎e̸͈̝͂̾s̶̫͍̫̾̀ş̸̘͊ ̴̪̈́̈́̊d̵͇͚̿̕ì̶̲͌d̵̘̃͊̈ǹ̵̹’̸̢̹̌̊ͅt̷̠̔̊̓ ̶͇͈̾l̴̼͉͎͝ȏ̴͎̙v̵̢̝͍͆̉ȩ̷͊̋ ̷̻̓h̶̤̱̋͘i̵̘̅͋̉ṃ̷̈́.̸̻̳̒̇͝ ̸̖̣́ͅT̴̟͐̏h̵̭̰͕̔ẻ̶̜̬͝͝ ̶̦̾́p̸̨̻̦̽ṛ̴͂i̶̢̜̓̍n̴̛̈́ͅĉ̶̱͇̅̆ḛ̴͝s̶͎͑̏s̶̤͌̇ ̷̥̓l̷̨̪̦̇͐͒o̸̢͋̈́v̶̝̲͒͝è̷̼̎ḏ̸̘̫̿͌̊ ̴͉̘̄t̵̢͖̲̅̈́̇h̸̟̲́ẹ̸́ ̶̦̊͋́d̷̞̋r̷̢̨͙͐a̵̖͐ğ̷̦̜o̵͙̬̐͒n̴͈̔.̴̖̫́͒͑”̵̞̊̕ ̸͓̬̆́ ̸̢̈́̎“̸͇̻̀͠N̷͉͝o̴͙̊̐̃b̸͓̝̭̑o̴̮͂͛͜ḑ̶̢̾̃̓͜ỹ̷̱͗̉ ̸͈̍͊c̶̻͍̐̀̿o̵͔̕u̶̪͒l̶̢̖͉̑d̴̡͈̣͆̉̚ ̸̨̦̳͂l̵̲̥̏͘͠ö̴͔͓́v̴͈̻͐̑͌ê̵̗̲͒̈́ ̶̲̎ẗ̷̗͈̪́̽h̸̛̺̳̤͗̋ĕ̶͎̗ͅ ̶̢̤̓͊d̸̹̐̎r̷̹͖̣̋̈́͊a̷͙̒̅g̶̞̈́̃o̶̯̣͆͂̐n̴̛̫̘͛͐.̸͎͈͆̾ ̶̗̼̝͒̃͐I̵̪͕͊f̶̧̖̮̈́ ̷̜̩̐͜͠͠a̶͚͛̈̑ṇ̷̣̎̃͘ͅy̶̽ͅt̴͕͚͉̅̐̕h̷̰̓̚i̷̡͌͝ͅń̵̲̭̊ğ̵̙ ̴̮̭̝̔̒̊t̸̛͍͉̝̑h̶͓͋e̷̤̤̋ ̸̺̍̈͝p̴̦͎̠͌́̔r̴͖̬̓ĩ̶̖͖͖n̶̡̗̄c̸͎̒͆e̶̮̒̈́̀s̴̡͓͗̎s̷̪͇̿ ̵̢̲̇̂̉ͅḭ̵͓̀s̸̗͕̘̊ ̷͚̂͜l̷̗̎͂͒û̷̢͔͊̄c̴̯͒̀͂k̶͔͐͑̃ý̵͎͆ ̴̧̛̹͌̏t̶̼͙͊͆ò̴̲ ̴͈̹̆h̴̖̐a̸̧͑͋v̷͚͝e̵̦̦̙͊̊ ̸̻͚̻͗̐͠a̷͙͉͛̇̀ ̶̰̝̑ͅp̵͎̍r̵̢͖̅ȋ̶̻n̶͉̈͋̅c̵̹͔̘̓e̶̙͚͚̅.̴̛̜̈́ ̴̼͌̍̎T̴͕̉ͅḧ̸̭́e̷̜̪̓ ̴̬͒̊̀p̸͈͋͘͝r̸̭̥̊͝i̸̧̱̅̍n̶̮͊̔ĉ̸̦̉̾͜e̸̯̍͐s̶̙̽s̴̛͔̰̻̒͆ ̶̡̥̥͐͐͑ẅ̸̞̞͈́̓̿ȃ̷̻̬́ͅs̶̡̧̳͒͐́ ̴̼̹͈́̏̕n̸̟̍͐o̴͎͉̊̀t̷̗͆͐̾ḫ̷̬̲͌͝i̷̛̠͑͘n̸̘̚͜ģ̴̰͐.̷͓̻́͠ ̶͔̮̓S̵̼̳͇͝ȟ̶̼̗̎͑ͅe̵̜̕͜ ̸͖͆͆͊ś̵͍͔̎̇ḩ̷́o̶̡͓̱̍̽̕u̶͎̽͐̃ļ̸̛̼̰̊̐d̷͙̣̏ ̵͚̕b̴̡̈́̂e̴͇͓͑̽ ̸̘͂͊̕m̴̢̓́͝ô̸̧̩̋r̷̖͕̊̃̚e̶̪̊ ̷̦͠g̸̲͆̚ř̶̗̝͌̿ͅa̶̛͉̾͊t̵̹͖̑͑̅ē̵̘̮̔f̶̫̄̕u̵̧̯̜̐͝l̵̹͌͘.̵̣͔̦́”̶̛͖̹ ̴̼̅͜ ̶̯͓̰͛̊͑ ̸̬̏̓“̵̝͐͛͝S̵̳̎o̸͇̗̜̓̅̚ȑ̵̰̹̈́̆r̶̼̘̋̇̇ͅý̷̟̞͇̉͗.̵̥̟̓̾̒.̸̧͍̠͗̆͂.̶̱̟͌̚I̵̮̽ ̴̹̆͂͜d̵̡͔̤̿ȋ̷͇ḏ̸̔n̷͓̩̙̑̀’̷̡̛̩̆t̶̬̟̓̆ ̶͖̉͐̾m̸͓̙̖̋ȅ̶̜̆a̶͖͚̞͛n̴̬̼̙̉̀ ̶̹̣̼̅̏̐t̸͎̭̳͠o̸̜̜̹̓͋ ̸̰̦̝͠ư̸̻̈́͘p̴̧̖͖̿s̵̪̺̔̽e̷̳͐̂ṱ̸͉͒ ̵̢͇͎̃ÿ̴̹͙́͘o̷͙̺̭̿̉͘ü̵̧̾͌.̴͚͑.̶̖̑̌.̸̮̘͖̓͆Í̴̗̳̣.̴̰͂̕.̴͇̰͓̂̚͝.̸̨̰͌Ï̵͍ ̶̨̺͙̿̿ḻ̴̝̍ŏ̷̜̠̾v̴̡͕̳̀̀͠e̶̪̓̑ ̴̖̅ẗ̸̠͎̈́̍h̵͙̜͂͂̈́e̵̖̰͙̍͒ ̸͎̹͐p̸͉̾̈̕r̴͖͋̈́i̷̩͆n̸̺͖̼̔ç̷̢̭͛͂e̸̺̫͎͒͝.̵̝́.̸͔̈.̵̜͖̎”̶̟͉͕̾ ̵̠̃́ ̶͉̓̐͝“̶̪͈̀͂͗H̵̨̅͝a̸̬̎̎̊ ̵̯̆̀h̵̙̑̿a̶̼̦͔͌̓͗.̵͉̓̍̒͜.̷̣̬͗̾̀.̸̦̮̻̀m̴͈̀͌̊e̶̟͋͘ ̸͙́͝ͅt̴̰̺̀͋͜o̶͔̲̹̓̑̑ő̸̢̠̗̚.̵̱̺͎͒.̵̡̡̛̩.̸̻͎̝͐͠”̸̯̜̯̀ ̷͓̿̚ ̷̮͍͂̄“̶̻̌ͅC̶͔̒͑͝ḁ̷͔̖̉n̷̥͚̓ ̵̧̆͑w̵̪̖̅e̶̙̱̽͆.̶̡̺̙͗.̶̛̛͕̮̓͜.̵͓̺̄̆̅ͅṙ̷͎͕̋͜e̶͔͐͝͝a̸͕̘̣͗̆d̶̪͛̄ ̷̹͈͖̈̕a̶̝͆͗͘n̶̢̲̈́̐͋ö̶̩̲̻t̴̥̓̅h̵̛͚̾e̴͈͚͚̾̍r̷̦̈.̸̣͖̳̓̒̏.̶͙̭̿.̴̞͌?̶͕̲͒͠”̶͔͇̼̒͂ ̴͚̤̅ ̵͕͛“̷͎̥̻̌D̸̯̙̈ä̷̡̒͜r̵̡̡̅̆l̶̙͎͕͊i̶̧̐n̸̗͘g̷̥̙̚,̸̯̲̭̈́̆Í̴̧ ̷̻̿̑̈́l̸̠͂̆̚o̴͚͊v̷͎̰͋̎ẹ̷͉̭͑̽̏ ̴̖͍͙̒̕r̴̨̿́̕ḙ̶͋̉a̷̩͑͆̎ḓ̵͆̉ȉ̸̪͔͗n̴̲̪̈̔̉g̶͇͐́ ̵̱̔͌͘ț̷̼͔́͐ḧ̷̘̳́e̴͖͚͛ṡ̶͈̈͘e̷̱͛́̀ ̴͓͔̻̈̚t̸̝̒̿͠o̴̢͗̏͝ ̵̇̐͜y̴̢̟̥̐͑̇o̸̞̙̔̿u̵̲̹̖̇͛ ̶̫̒̐b̵̯̍̾͊u̴̧͗͠͝t̶̬́̄̃ ̸̳̈́į̷͊t̶̹͛͌’̵̜̄s̶̲̜̎̈́ͅ ̶͙̺͊͌̈́n̷̞͝ě̶̼͔͉͐̄ạ̴̩͛r̷͙͕͉̐̀l̴̲̦͛̃͂y̸̖̳͎̿̄ ̴̥̩̤͒t̴̟̹̼͊͑ḯ̸͇̱m̷͓̥̚ē̵̜͊̔ ̶̯͕̥̏͊̕f̵̳͑̀ô̶̢̟͖r̴͔͍̉ͅ ̷̟̓͛b̶̟̰̔͂̕ḙ̶̟́d̴̮̦̀͒̌.̵̙̥͠ ̶̪͋M̴̡͔̪̉͝á̴̟͔̀͘ÿ̴̱́́̇b̶̲̙̓͌̃ͅe̸̥͎͉̿͂ ̷̠̟̼͗t̷͇̍̈́ộ̵̰̒̚m̴͙̙̆̒̋o̶͕͋͒̈́ṟ̵̨̠͘r̷͚̺͇̋̂o̷͙̪̐̚w̶̰̳̠͌,̸̢͙̹̔͘K̶͖͔͓̔a̴̬͓͚̐̇y̴̝͠?̸̦̖̋́̓”̷̢̭͋

“̵̦͙̱̽D̵̩͕͈̽á̵͚͓͋̚m̴̢̫̖͋̍n̶̙̯̣̐ ̷̠́d̵͚͕̿͊̉r̴͙͋̀a̶̭̒ģ̵̗́ő̶̜̗̘n̴̠͛͑.̴̧͈͙͆.̸̟̘̍.̴̼̉”̶͎͙͋͑̕