TPerson = class
FID:Integer;
….
property ID:Integer read FID write FID;

type
  TField = record
    FName: string;
    FValue: Variant;
  end;

type
  TBase = class
  private
    FFields: TList<TField>;
    function GetField(const AName: string): Variant;
    procedure SetField(const AName: string; const AValue: Variant);
  protected
  public
    property Fields[const ANames: string]: Variant read GetField write SetField; default;
    constructor Create(ANames: array of string);
    destructor Destroy;

  end;

implementation

{ TBase }

constructor TBase.Create(ANames: array of string);
var
  AField: TField;
  I: Integer;
begin
  FFields := TList<TField>.Create;
  for I := Low(ANames) to High(ANames) do
  begin
    AField.FName := ANames[I];
    AField.FValue := null;
    FFields.Add(AField);
  end;
end;

function TBase.GetField(const AName: string): Variant;
var
  I: Integer;
begin
  Result := null;
  for I := 0 to FFields.Count - 1 do
    if FFields[I].FName = AName then
      Result := FFields[I].FValue;
end;

procedure TBase.SetField(const AName: string; const AValue: Variant);
var
  I: Integer;
  TempRec: TField;
begin
  for I := 0 to FFields.Count - 1 do
    if FFields[I].FName = AName then
    begin
      TempRec := FFields[I];   // способ 1
      TempRec.FValue := AValue;
      FFields[I] := TempRec;
    end;
end;

end.

FDictionaryList = Dictionary<String, TField>