SQL> ed
Wrote file afiedt.buf

  1  with t as(
  2  select 1 id,'ВАСЯ' name from dual union all
  3  select 2,'ЮЛЯ' from dual)
  4  , tt as (
  5  select
  6   t2.*
  7  ,SUBSTR (T2.NAME, LEVEL, 1) s
  8  from t t2
  9   CONNECT BY LEVEL <= LENGTH (T2.NAME)
 10   and t2.id=prior t2.id
 11   and prior sys_guid() is not null)
 12  select
 13    id
 14   ,max(name) name
 15   ,LISTAGG (s) WITHIN GROUP (ORDER BY s) ls
 16  from tt
 17* group by id
SQL> /

        ID NAME LS
---------- ---- ----------
         1 ВАСЯ АВСЯ
         2 ЮЛЯ  ЛЮЯ